LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


OF 


~tr 


JAMES    WATT 
The  father  of  the   Modern    Steam   Engine. 


PUMPING  ENGINES 

FOR 

WATER  WORKS 


BY 

CHARLES   ARTHUR   HAGUE 

MEM.  AM.   Soc.  C.  E. 
MEM.  AM.  Soc.  M.  E. 
MEM.  AM.  W.  W.  A. 
MEM.  NEW  ENGLAND  W.  A. 


OF  THE 

UNIVERSITY 

OF 


NEW   YORK 

McGRAW   PUBLISHING  COMPANY 
1907 


GENERAL 


COPYRIGHT,  1907, 

BY    THE 

McGRAW  PUBLISHING  COMPANY 
NEW  YORK 


Stanhope  press 

.      O  I  L  8  O  N       COMPART 
•  G»TON,      U.S.A. 


DEDICATION 


THIS  BOOK  is  DEDICATED  TO  MY  FRIEND 
AND  PHYSICIAN 

DR.  JOSE  F.  DE  F.  FERNANDEZ. 


173029 


PREFACE 


THE  writer  is  well  aware  of  what  it  means  to  add  another 
book  to  those  already  in  existence  upon  the  subjects  of  Engineer- 
ing, Mechanics,  and  Machinery,  and  therefore  feels  somewhat 
obliged  to  say  a  word  or  two  which  might  seemingly  justify  his 
position  in  so  doing. 

This  history  of  pumping  machinery  to  a  very  limited  extent; 
this  setting  forth  of  a  few  general  principles;  this  description  of 
the  leading  types  and  classes  of  engines  used  for  pumping  water 
for  municipal  or  public  supply;  in  short,  the  contents  of  this 
book  are  not  produced  for  the  purpose  of  introducing  any 
specially  new  subject  matter,  but  rather  because  it  is  desired 
upon  the  writer's  part  to  make  an  attempt  to  attract  the  inter- 
est of  the  great  mass  of  students,  engineers,  water  works  man- 
agers, and  the  men  who  attend  to  the  practical  operation  of 
pumping  engines  in  service,  by  presenting  to  them  a  well  known 
subject  in  a  form  which  it  is  hoped  will  hold  their  attention 
in  a  pleasant  and  profitable  manner,  besides  encouraging  them 
to  think  about  what  they  are  reading. 

Books  written  upon  subjects  kindred  to  this  one  have  been 
in  many  cases  handled  in  a  masterful  manner  from  time  to 
time,  and  by  very  high  authorities.  But  there  is  a  general 
feeling  abroad,  approaching,  if  not  even  quite  amounting  to  a 
certainty,  of  aversion  to  deep  and  complex  mathematical 
explanations  and  exhaustive  and  exhausting  technical  discus- 
sion, with  which  text  books  and  reference  books  abound. 
Therefore  it  is  proposed  herein  to  exhibit  the  work  without  a 
display  of  the  tools  by  means  of  which  such  work  has  been 
accomplished,  and  it  is  supposed  by  the  writer  that  this  course 

iii 


Iv  PREFACE 

will  excite  the  greatest  attention,  and  give  the  most  of  useful 
facts,  with  the  least  labor  to  the  reader.  This,  accompanied 
by  the  touchstone  of  personal  experience,  will,  it  is  hoped,  make 
a  strong  appeal  to  human  interest. 

Those  about  to  take  up  or  to  extend  the  study  of  steam 
engines,  pumps,  and  pumping  engines,  are  often  discouraged 
at  the  very  start  from  approaching  the  matter  as  closely  as 
they  desire,  by  the  complicated  character  of  the  opening  pages 
of  a  great  many  of  the  text  books;  and,  although  natural  laws 
and  their  principles  and  effects  must  be  necessarily  wrestled 
with  to  a  very  serious  extent  by  the  student  at  school, 
and  others  later,  by  way  of  substantial  foundation  for  after 
life,  it  seems  as  though  there  might  be  a  small  space  available 
for  a  book  which  deals  with  the  subject  in  a  somewhat  primi- 
tive manner,  in  plain  e very-day  words,  without  taking  too 
much  knowledge  for  granted  upon  the  part  of  the  reader,  and 
with  the  almost  total  absence  of  mathematical  details.  If  the 
student  or  the  layman  hesitates  at  the  smaller  books,  some  of 
which  are  really  too  brief  upon  important  points  and  often 
assume  too  much  knowledge  of  principles  and  details  upon  the 
part  of  the  reader,  then  it  may  be  imagined  with  what  thoughts 
and  feelings  the  beginner  or  the  seeker  after  knowledge 
approaches  the  larger  books,  which  go  so  thoroughly  into 
minute  details.  Besides  all  this,  even  a  person  of  experience 
Hkes  to  see  something  in  print  which  clearly  and  unmistakably 
coincides  with  his  own  views.  It  makes  him  feel  that  he  is  not 
mistaken  in  his  own  course  and  ideas,  which  is  more  or  less 
assuring  to  anyone. 

In  the  f  blowing  pages  it  has  been  considered  best  to  com- 
mence at  cnce,  after  a  few  words  of  introductory  character 
and  of  historical  interest,  with  a  description  of  the  highest 
attainments  of  pumping  engines  and  a  comparison  between  the 
nearest  practicable  approach  as  shown  by  the  Mariotte  curve, 
to  theoretical  lines  in  steam  expansion,  and  the  actual  practice 
of  building  and  operating  such  machinery  upon  a  large  scale. 
In  this  way  a  sort  of  reflected  object  lesson  is  brought 


PREFACE  V 

before  the  mind  with  a  very  near  approach  to  a  practical 
demonstration  of  the  principles  involved;  and  after  this  intro- 
duction, bringing  in  only  the  most  important  points  such  as 
initial  or  boiler  pressures,  ratios  of  steam  expansion,  theoretical 
and  best  actual  vacuum,  receiver  and  counter  pressures, 
steam  jackets  and  the  amount  of  steam  used  or  wasted  in 
such  jackets;  the  subject  is  then  carried  along  natural  lines 
touching  upon  the  relations  between  steam  and  coal  con- 
sumption, the  investment  value  and  costs  of  pumping  plants, 
taking  in  the  various  types  and  classes  of  pumping  engines 
past  and  present,  with  mention  of  a  few  of  the  more  promi- 
nent details  of  construction,  kinds  and  qualities  of  materials, 
and  finally  finishing  with  the  principles  and  practices  in- 
volved in  duty  tests  of  pumping  machinery  for  water  works 
service. 

Now,  this  demonstration  by  means  of  drawings,  figures,  and 
pictures  alone,  is  nothing  like  so  easy  or  effective  as  contact 
and  experience  with,  or  even  observation  of,  the  machinery 
itself;  and  since  the  subject-matter  herein  cannot  possibly  be 
learned  from  books  alone,  it  is  strongly  recommended  by  the 
writer  that  the  thoughts  the  reading  of  this  book  may  give 
rise  to,  be  supplemented  by  the  observation  of  pumping  engines 
in  operation,  and  as  much  practical  experience  as  it  may  be 
convenient  or  possible  to  acquire.  In  fact  it  is  assumed  that 
this  book  is  to  be  used  either  to  finish  up  a  course  at  school 
or  college,  or  to  assist  a  practicing  engineer,  or  a  running  engi- 
neer at  a  pumping  station,  or  a  fireman  in  the  boiler  room,  or 
water  works  managers  and  superintendents,  to  understand  what 
can  be  done  with  a  pumping  engine  under  various  conditions 
and  in  different  situations. 

The  view  has  been  taken  herein,  that  the  reader,  especially 
if  he  is  a  beginner,  should  not  be  confused  at  the  start  by  men- 
tioning numberless  possibilities  and  conditions,  no  matter  if 
they  may  be  extremely  interesting  on  their  own  account.  The 
aim  has  been  rather  to  present  types  and  classes,  and  to  impress 
upon  the  reader's  and  the  student's  attention  the  fact  that 


yi  PREFACE 

after  all,  such  types  and  classes  of  machinery  are  subject  to 
numerous  modifications  and  variations  in  order  that  the  ever 
changing  and  differing  conditions  found  at  different  pumping 
stations  may  be  effectively  met  to  the  best  advantage,  all 
things  considered. 

CHARLES  ARTHUR  HAGUE. 

NEW  YORK,  1907. 


CONTENTS 


CHAPTER  FAGB 

I   THE  PUMPING  ENGINE 1 

II   HISTORICAL 8 

III  ECONOMIC  STEAM  DUTY 22 

IV  THE  ADVENT  OF  TRIPLE  EXPANSION      35 

V   THE  MARIOTTE  CURVE 47 

VI    STEAM  JACKETS 63 

VII   COAL  DUTY  OF  PUMPING  ENGINES 79 

VIII   ACTUAL  CONDITIONS  OF  PUMPING    .    .    ;    .    .  ^  .    .    .    .  92 

IX   THE  WORTHINGTON  DUPLEX  PUMPING  ENGINE    ....  105 

X   THE  HOLLY  QUADRUPLEX  PUMPING  ENGINE 122 

XI   THE  GASKILL  PUMPING  ENGINE       133 

XII   THE  REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    .  143 

XIII  VARIOUS  TYPES  AND  CLASSES 166 

XIV  PUMPING  ENGINES  ADAPTED  TO  CONDITIONS 185 

XV   INSTALLATION  OF  PUMPING  ENGINES      198 

XVI   INVESTMENT  VALUE  OF  PUMPING  ENGINES 216 

XVII   SUCTION  LIFT  AND  SUCTION  PIPES      23O 

XVIII    WATER  PASSAGES  AND  WATER  VALVES 241 

XIX   THE  WATER  PLUNGERS 25O 

XX   AIR  CHAMBERS 267 

XXI   STEAM  PISTON      275 

XXII   STEAM  CYLINDERS 288 

XXIII  CROSS  HEADS 304 

XXIV  FRAMES  AND  BEDPLATES 314 

XXV   MATERIAL  FOR  PUMPING  ENGINES 331 

XXVI    DUTY  TESTS  OF  PUMPING  ENGINES  345 


ILLUSTRATIONS 

FIGURE  PAGE 

1  Hero's  Steam  Engine      9 

2  Savery's  Pumping  Engine      10 

3  Model  of  Papin's  Piston  Engine 11 

4  Newcomen's  Pumping  Engine 12 

5  Leupold's  Pumping  Engine 13 

6  Watt's  Engine,  1769 17 

7  Watt's  Engine,  1781 20 

8  Watt's  Engine,  1784 21 

9  Simpson's  Pumping  Engine,  1848 30 

10  The  Mariotte  Curve  in  a  Single  Cylinder 51 

11  The  Mariotte  Curve  Through  Three  Cylinders 53 

12  The  Mariotte  Curve  in  a  Single  Cylinder  in  Practice 56 

13  The  Mariotte  Curve  in  Triple  Engine  in  Practice      57 

14  The  Mariotte  Curve  Showing  Range  of  Temperature 75 

15  The  Original  Worthington  Low  Duty  Pumping  Engine 106 

16  Standard  Rubber  Valve  and  Seat 110 

17  Worthington  High  Duty  Horizontal  Compound,  Perspective      ...  112 

18  Worthington  High  Duty  Horizontal  Compound,  Sectional      ....  114 

19  Worthington  Compensating  Cylinder  Diagram      115 

20  Worthington  Horizontal  Compound,  High  Duty 116 

21  Worthington  Horizontal  Triple,  High  Duty facing  page  116 

22  Low  Duty  Worthington  Triple,  Horizontal facing  page  117 

23  Worthington  Vertical  Triple,  High  Duty 118 

24  Holly  Quadruplex  Pumping  Engine,  Perspective       124 

25  Holly  Quadruplex  Pumping  Engine,  Sectional       125 

26  Gaskill  Horizontal  Compound  Pumping  Engine,  Perspective      .    .    .  134 

27  Gaskill  Horizontal  Compound  Pumping  Engine,  Sectional      ....  136 

28  Gaskill  Horizontal  Triple  Pumping  Engine facing  page  136 

29  Pump  Valves  of  Gaskill  Engine 138 

30  Latest  Gaskill  Horizontal  Compound  Pumping  Engines,  facing  page  140 

31  Latest  Gaskill  Horizontal  Compound  Pumping  Engines,  facing  page  141 

32  Reynolds  Beam  Pumping  Engine,  Milwaukee .    .  144 

33  Sectional  View  of  Reynolds  Beam  Pumping  Engine 145 

34  Reynolds  Three  Cylinder  Compound  Pumping  Engine 146 

35  Reynolds  Three  Cylinder  Compound  Pumping  Engine 148 

36  Cage  Construction  of  Pump  Valve  Seats 150 

37  Cage  Construction  of  Pump  Valve  Seats 151 

38  Steam  End  of  Reynolds  St.  Paul  Pumping  Engine 152 

39  Reynolds  Triple  Expansion  Pumping  Engine 154 


x  ILLUSTRATIONS 

FIGURE  PAOB 

40  North  Point,  Milwaukee,  Triple  Pumping  Engine 156 

41  Reynolds  Self-Contained  Triple  Pumping  Engine      .    .     facing  page  158 

42  Air  Chambers  Supporting  One  End  of  Bedplates      162 

43  Compound  Non-Condensing  Worthington  Engine     .    .     facing  page  168 

44  Low  Duty  Worthington  Triple  Expansion  Pumping  Engine 

facing  page  170 

45  Section  Through  Worthington  Triple  Cylinders     .    .    .     facing  page  171 

46  Worthington  Horizontal,  High  Duty  Triple 171 

47  Worthington  Vertical,  High  Duty  Triple 172 

48  Snow  Horizontal  Cross  Compound  Pumping  Engine     .     facing  page  172 

49  Allis-Chalmers  Horizontal  Cross  Compound  Pumping  Engine 

facing  page  173 

50  Platt  Iron  Works  Company  Horizontal  Cross  Compound 173 

51  Allis-Chalmers  Vertical  "A"  Frame  Compound     .    .    .     facing  page  174 

52  Allis-Chalmers  Vertical  Tower  Frame  Compound  and  Triple 

facing  page  175 

53  Gaskill  Horizontal  Triple  Pumping  Engine facing  page  176 

54  General  View  of  d'Auria  Pumping  Engine facing  page  177 

55  Hydraulic  Loop  of  d'Auria  Pumping  Engine 177 

56  Platt  Iron  Works  Company  Compound   Direct  Acting  Pumping 

Engine facing  page  178 

57  Platt  Iron  Works  Company  Cross  Triple  Direct  Acting  Pumping 

Engine facing  page  179 

58  General  View  of  Groshon  Pumping  Engine 180 

59  Side  Elevation  of  Groshon  Pumping  Engine      181 

60  Corliss  Pawtucket  Pumping  Engine,  by  George  H.  Corliss      ....  182 

61  Leavitt  Lawrence  Pumping  Engine,  by  E.  D.  Leavitt 183 

62  Reynolds  Milwaukee  Pumping  Engine,  by  Edwin  Reynolds   ....  184 

63  Foundations  on  Rock  inside  of  Pumping  Station      204 

64  Engine  Foundations  on  Concrete  Piling      207 

65  Engine  Foundations  on  Concrete  Piling      208 

66  Typical  Pump  Valve  for  Water  Works  Engines 243 

67  Typical  Pump  Valve  for  Water  Works  Engines 244 

68  Diagram  of  Crank  and  Plunger  Movements 253 

69  Plunger  and  Ring  Pump 259 

70  Inside  Packed  Plunger / 261 

71  Center  Packed  Horizontal  Plunger 262 

72  Center  Packed  Vertical  Plunger 263 

73  Vertical,  Outside  Packed  Differential  Plunger 264 

74  Vertical,  Outside  Packed  Single  Acting  Plunger 264 

75  Steam  Piston,  16  inches  Diameter 277 

76  Steam  Piston,  23  inches  Diameter 279 

77  Steam  Piston,  30  inches  Diameter 281 

78  Steam  Piston,  56  inches  Diameter 284 

79  Steam  Piston,  84  inches  Diameter 285 

80  Section  of  Steam  Jacket  Cast  on  the  Cylinder 292 


ILLUSTRATIONS  xi 

FIGURE  PAOE 

81  Section  of  Steam  Jacket  Cast  on  the  Cylinder 292 

82  Reynolds  Steam  Jacket,  Separate  from  Cylinder 292 

83  Bottom  Cylinder  Head  with  Reynolds  Steam  Jacket 293 

84  Enlarged  Section  of  Upper  End  of  Cylinder  and  Jacket 293 

85  Section  of  Cylinder  Head  with  Corliss  Valves      294 

86  Section  of  Steam  Cylinder  with  Side  Pipes 294 

87  Cylinder  Section  with  Ribs  and  Pipe  Nozzles       295 

88  Poppet  Valves  Closed 296 

89  Steam  and  Exhaust  Valves  off  the  Seats      296 

90  Ports  of  Corliss  Valves  across  the  Heads       297 

91  Ports  of  Corliss  Valves  across  the  Heads      297 

92  Leavitt  Steam  Jacket,  Designed  by  E.  D.  Leavitt      299 

93  Enlarged  Section  of  Leavitt  Steam  Jacket 300 

94  Cross  Head  of  Early  Worthington  Engine 305 

95  Later  Worthington  Cross  Heads 306 

96  Early  Gaskill  Cross  Heads,  High  and  Low  Pressure 307 

97  Later  Gaskill  Cross  Heads 308 

98  Cross  Heads  of  Cross  Compound  Pumping  Engine 309 

99  Worthington,  Vertical,  High  Duty  Cross  Head 310 

100  Forged  Steel  Cross  Head  for  Vertical  Triple  Engine 311 

101  Cast  Steel  Cross  Head  for  Vertical  Triple  Engine 312 

102  Framing  of  Holly  Quadruplex  Pumping  Engine      318 

103  Framing  of  Later  Worthington  Pumping  Engine 319 

104  Framing  of  Later  Gaskill  Pumping  Engine       ....     facing  page  320 

105  Allis-Chalmers  Cross  Compound  Framing facing  page  321 

106  Platt  Iron  Works  Cross  Compound  Framing 321 

107  Snow  Cross  Compound  Framing 322 

108  Vertical  Pumping  Engine  with  Two  Piers,  Holly  Manufacturing 

Company facing  page  322 

109  Vertical  Pumping  Engine  with  One  Pier 324 

110  Vertical  Pumping  Engine  with  all  "A"  Frame 325 

111  Latest  Type  of  Self-Contained  Engine,  Irving  H.  Reynolds 

facing  page  326 

112  Framing  of  Worthington  Vertical  Triple  Engine 329 

113  Main  Pillow  Block  for  Crank  Shaft    .                                                  ,  341 


PUMPING  ENGINES  FOR  WATER  WORKS 

CHAPTER   I 
THE  PUMPING  ENGINE 

WHEN  a  substance,  as,  for  example,  coal,  goes  through  the 
process  of  burning  in  a  furnace  and  makes  what  is  known  as 
fire,  a  particular  form  of  energy  is  produced  termed  heat;  and 
such  a  process  is  called  combustion. 

If  the  heat  is  applied  to  a  fluid,  as,  for  example,  water,  a 
form  of  gas  is  produced;  and  such  a  gas  is  called  steam.  The 
temperature  at  which  steam  is  produced  varies  with  the  pres- 
sure; at  ordinary  atmospheric  pressure  the  temperature  is  212° 
Fahrenheit. 

When  steam  is  formed  within  a  vessel  not  closed,  as,  for 
example,  a  teakettle,  the  pressure  will  remain  that  of  the 
atmosphere,  and  the  temperature  at  212°  Fahrenheit.  If  the 
steam  is  confined  in  a  closed  vessel,  as,  for  example,  a  steam 
boiler,  the  pressure  can  be  utilized;  and  the  greater  the  amount 
of  heat  applied  to  the  boiler,  the  more  steam  will  be  made, 
the  greater  the  amount  which  can  be  utilized,  and  the  greater 
the  temperature  and  pressure  will  be. 

From  the  boiler  the  steam  can  be  conveyed  through  a  pipe 
to  a  closed  receptacle  known  as  a  cylinder;  and  within  this 
cylinder  can  be  placed  a  disk  called  a  piston,  fitted  to  a  rod; 
the  piston  is  capable  of  moving  freely  in  the  cylinder..  The 
steam  can  press  the  piston  forward  and  backward,  or  upward 
and  downward,  as  the  case  may  be,  within  the  cylinder,  and  so 
produce  motion  of  the  piston  rod. 

The  motion  of  the  piston  rod,  impelled  by  the  piston,  which 
r'n  turn  is  driven  by  the  pressure  of  the  steam  within  the  cyl- 
inder, is  employed  in  many  ways  as  shown  by  the  great  variety 
of  forms  and  work  of  the  steam  engine.  In  this  book,  however 9 


2  PUMPING  ENGINES 

the  work  of  the  steam  engine  is  considered  only  with  reference 
to  the  pumping  of  water  for  public  supply,  and  in  the  form  of 
steam  machinery  known  as  the  water  works  pumping  engine, 
which  is  a  machine  consisting  of  one  or  more  steam  cylinders 
and  one  or  more  water  cylinders,  with  appropriate  supports, 
framing,  and  working  parts,  so  as  to  utilize  the  heat  energy  in 
the  useful  work  of  pumping. 

The  first  duty  of  a  pumping  engine  is  to  PUMP  WATER;  to 
do  this  successfully  and  continuously.  And  it  matters  little 
what  else  it  can  do  if  it  cannot  do  this.  If  it  fails  in  this,  it 
fails  in  its  most  important  mission  and  in  its  reasons  for 
existence. 

Next  to  reliability  and  durability  in  continuous  operation, 
comes  economy  in  steam  consumption.  And  to  combine  relia- 
bility, durability,  and  steam  economy,  a  great  deal  of  thought, 
study,  and  effort,  have  been  expended  upon  the  pumping  engine 
for  more  than  a  hundred  years. 

There  have  been  pumping  engines  designed  and  built  in  which 
the  repairs  have  been  excessive,  and  the  necessary  stoppages 
have  been  costly,  troublesome,  and  annoying;  although  when 
actually  in  operation  steam  economy  has  been  reasonably  high. 
Some  engines  meeting  fairly  well  the  requirements  of  steam 
economy,  but  lacking  in  durability,  have  something  radically 
wrong  in  their  makeup  or  in  their  adaptation  to  the  conditions 
of  the  work  to  be  done. 

The  necessity  for  staying  qualities  must  be  clearly  recog- 
nized at  all  times,  although  at  each  successive  step  along  the 
line  of  changed  economic  conditions,  new,  or  at  least  different 
difficulties  in  the  matter  of  construction  and  of  working  forces 
have  been  successively  met  and  provided  for,  until  to-day  it 
looks  very  much  as  if  the  practical  and  indeed  the  theoretical 
limits  of  design  and  efficiency  have  been  at  last  reached. 

There  have  been  pumping  engines  designed  and  built  in 
which  the  repairs  have  been  next  to  nothing,  or  at  least  at  a 
very  low  rate,  although  such  pumping  engines  have  been  in 
nearly  continuous  service  for  over  twenty  years.  Such  engines 


THE  PUMPING  ENGINE  5 

have  met  to  a  very  satisfactory  degree  the  requirements  of 
reliability  and  durability,  but  have  been  considered  low  in 
steam  economy. 

And  so  for  many  years  there  has  been  urged  a  sort  of  engi- 
neering and  commercial  warfare  between  the  contending  forces 
representing  low  and  high  economy  in  steam  consumption,  or, 
according  to  the  old  war  cries  so  well  known  and  remembered 
by  those  who  were  active  in  the  water  works  field  twenty  years 
ago,  "low  duty"  and  "high  duty." 

The  simplicity  and  directness  of  the  best  types  of  the  low 
duty  pumping  engines  have  never  been  equaled  by  the  high 
duty  machines.  Simplicity  of  construction  seems  to  be  a  com- 
panion of  low  duty;  and  it  seems  to  be  impossible  to  separate 
comparative  complication  from  high  duty.  The  value  of  coal, 
the  value  of  capital,  and  the  daily  capacity  per  unit,  have  been 
important  factors  in  the  problem.  And  so  the  contest  has 
gone  on  until  with  greatly  increased  pumping  capacity  in  a 
single  engine ;  greatly  modified  cost  in  construction,  partly  from 
simpler  designs  and  partly  from  better  shop  management; 
greatly  reduced  rates  of  bond  interest  ranging  from  8  per  cent 
in  1873,  down  to  3J  per  cent  at  the  present  time;  station 
duties  based  on  all  coal  burned,  ranging  from  111,000,000  to 
135,000,000  annually,  with  a  low  rate  of  repairs;  with  all  these 
and  some  minor  items,  the  high  duty  pumping  engine  has 
forged  ahead  and  to  the  front,  and  the  low  duty  engine  has  been 
relegated  to  rather  small  capacities  where  fuel  is  very  cheap. 

But  of  course  Rome  was  not  built  in  a  day,  and  no  matter 
how  clearly  the  higher  attainments  may  now  appear,  the  road 
to  these  attainments  in  modern  pumping  engineering  has  been 
long,  expensive,  and  troublesome  to  travel,  both  for  builders 
and  for  buyers.  And  as  in  all  engineering  endeavors  to  improve 
the  lot  of  mankind  by  means  of  the  adaptation  of  natural  forces 
and  resources  to  his  use,  notwithstanding  the  hard  work,  occa- 
sional fallings  out,  and  even  threatened  warfare  so  to  speak, 
the  inherent  and  everlasting  good  will  which  is  really  at  the 
bottom  of  industrial  progress  persistently  holds  its  own. 


4  PUMPING  ENGINES 

It  is  not  the  purpose  of  this  book  to  consider  what  at  the 
present  time  would  be  termed  ancient  methods  of  raising  water, 
although  the  fact  was  evidently  recognized  a  long  time  ago, 
that  progress  in  the  well-being  of  mankind  depended  a  very 
great  deal  indeed  upon  a  plentiful  supply  of  water;  good  and 
wholesome  if  possible,  but  water  at  all  events.  The  particular 
point  of  good  and  wholesome  water  did  not  then  have  to  be 
driven  home  so  incisively  for  the  good  and  simple  reason  that 
the  opportunities  for  pollution  and  unwholesomeness  were  much 
less  frequent  centuries  ago  than  now,  at  this  time  we  call  the 
present,  when  the  great  concentration  of  inhabitants  now  to 
be  observed  as  taking  place  in  all  parts  of  the  civilized  world. 

No  attempt  has  been  made  herein,  in  fact  quite  the  contrary, 
to  exhibit  the  tools  so  to  speak,  such  as  intricate  rules  and 
formulae,  with  which  the  work  of  the  book  has  been  accom- 
plished; and  all  statements  of  facts,  and  all  views  of  the  writer, 
have  been  brought  down  to  plain  and  simple  language  so  far 
as  the  technical  nature  of  the  subject  will  permit.  Further, 
it  is  not  the  purpose,  and  it  is  not  hoped,  to  teach  very  much 
to  the  regular  designers  and  manufacturers  of  pumps  and  pump- 
ing machinery,  although  judging  from  past  performances,  a 
hint  or  two  in  their  direction  now  and  then  would  not  be  amiss; 
and,  therefore,  all  ideas  of  giving  instruction  to  designers  and 
manufacturers  will  be  limited  to  the  pointing  out  of  the  fact 
that  a  dead  engine  in  the  shop,  being  built  and  put  together 
in  a  sort  of  preliminary  way,  and  necessarily  so  of  course,  is. 
a  totally  different  animal  so  to  speak,  from  the  live  machine 
under  steam  and  water  pressure,  doing  work  in  its  actual  field 
of  usefulness.  This  difference  does  exist,  as  the  writer  knows 
from  experience  during  something  like  thirty  years,  and 
embraces  all  kinds  and  qualities  of  designers  and  builders. 
None  escape.  And  it  is  useless  and  a  waste  of  time  to  try  to- 
escape  entirely.  The  thing  to  do  is  to  carefully  design  a  pump- 
ing engine  to  suit  the  conditions  presented,  and  see  that  the 
designer  gets  the  right  conditions;  have  his  drawings  made  by 
experienced  men,  have  the  work  put  through  the  foundry,  the 


THE  PUMPING  ENGINE  5 

forge,  the  machine  shop,  and  the  different  highways  and  byways 
of  construction,  ship  it  to  its  destination  and  erect  it  upon  the 
foundations  prepared.  And,  whatever  in  the  way  of  human 
weakness  there  may  be  reflected  in  the  machine,  put  it  down  in 
the  experience  book  for  future  avoidance  or  use,  do  the  best 
that  can  be  done  and  let  it  go  at  that.  All  seem  to  fare  alike, 
the  commercial  product  from  the  highest  sources,  the  special 
design  rprcially  built  at  fifty  per  cent  advance  over  the  com- 
mercial article,  and  the  veriest  runt  of  a  machine  that  ever 
attempted  to  pump  water.  And  this  is  not  written  in  a  spirit 
of  blame;  but  to  state  a  condition  of  things  inseparable  from 
human  nature,  and  to  let  the  buyer  of  pumping  engines  know 
the  hopelessness  of  seeking  perfection  according  to  his  pet  ideas. 

But  there  are  a  large  number  of  people  aside  from  manufac- 
turers greatly  interested  in  the  subject  of  water  works  pump- 
ing engines.  Those  who  buy  such  machinery  either  for  their 
own  investments  or  as  representatives  of  municipal  corpora- 
tions; those  who  endeavor  to  advise  and  counsel  in  the  adapta- 
tion of  different  classes  and  types  of  pumping  machinery  to 
various  situations;  and  those  who  have  the  care  and  responsi- 
bility of  such  machinery  in  its  daily  operation.  In  other  words 
this  book  is  intended  mostly  for  the  owners  of  water  works 
plants,  such  as  water  works  companies;  for  water  commis- 
sioners, boards  of  public  works,  and  similar  municipal  author- 
ities; for  city  engineers,  consulting  engineers,  and  professional 
engineers  generally  who  are  interested  in  the  subject  of  the 
installation  of  water  works  engines;  and  for  the  men  in  the 
office,  in  the  engine  room,  and  in  the  boiler  room,  who  are 
responsible  for  the  economy  and  efficiency  of  the  plant  all 
along  the  line  from  the  coal  pile  in  the  bunker,  to  the  water 
supply  in  the  reservoir  or  distribution. 

The  importance  of  public  water  supply  can  scarcely  be 
overestimated  in  connection  with  the  life  and  growth  of  cities 
and  towns,  and  indeed  is  only  limited  by  the  value  of  the  cities 
and  towns  themselves.  Just  at  the  present  time  the  subject  is- 
of  particularly  widespread  interest,  covering  the  items  of  quan- 


6  PUMPING  ENGINES 

tity,  quality,  supply,  economy,  and  distribution.  Those  for- 
tunate communities  so  situated  that  impounded  gravity  supplies 
of  water  are  practicable  and  available,  are  comparatively  few 
in  number;  and  even  at  that,  after  the  main  supply  has  been 
delivered  for  distribution,  it  is  found  that  the  necessity  often 
arises  for  providing  methods  for  supplying  the  higher  districts 
of  a  city  by  means  of  supplementary  or  "high  service"  pump- 
ing. Indeed  the  very  fact  that  a  city  is  situated  where  hills 
are  high  enough  and  near  enough  to  provide  a  gravity  supply 
of  water,  indicates  by  the  general  formation  of  the  country 
that  high  service  conditions  are  extremely  possible  in  the  city 
itself.  But  apart  and  aside  from  the  few  cases  of  gravity  sup- 
ply, very  many,  in  fact  a  great  majority  of  cities  and  towns 
depend  upon  pumping  for  both  their  main  and  auxiliary  sup- 
plies of  water,  and  in  passing  it  might  be  well  to  mention  that 
the  relative  desirability  of  gravity  and  pumping  supplies  in 
their  order  of  value  seems  to  be  as  follows: 

Gravity  supply  from  lakes  or  impounded  streams  at  proper 

elevations. 
Gravity  main  supply  with  auxiliary  pumping  for  high  service. 

Reservoirs. 
Gravity  supply  with  auxiliary  pumping  supply  for  all  services. 

Reservoirs. 
Pumping  from  streams  or  lakes  to  storage  and  distributing 

reservoirs. 
Pumping  from  streams  or  lakes  to  standpipes  for  distribution. 

No  storage. 
Pumping  from  streams  or  lakes  directly  to  distribution.     No 

standpipes. 

The  importance  then  of  the  water  works  pumping  plant,  and 
of  the  pumping  engine  itself  may  be  easily  comprehended  by 
the  most  casual  investigator  of  the  subject.  And  following 
this  line  of  thought  the  questions  of  desirability,  capacity, 
type  best  adapted,  highest  practicable  measure  of  real  economy 


THE  PUMPING  ENGINE  7 

in  operation,  and  other  appropriate  details  come  immediately 
to  the  front.  But  before  going  into  particulars  as  minutely 
and  closely  fitting  as  may  be,  in  the  absence  of  specified  cases 
to  deal  with,  it  will  be  of  interest  no  doubt  and  also  a  fair  guide 
to  the  mind  to  briefly  review  the  steps  heretofore  taken  in  the 
past,  by  the  investigators  and  producers  of  pumping  machin- 
ery, constantly  spurred  on  by  competition  in  business  and  by 
the  pride  of  accomplishment,  until  to-day  a  point  has  been 
reached  not  even  dreamed  of  three  or  four  decades  ago.  And 
as  we  pause  and  glance  backward  along  the  roadway  of  prog- 
ress, there  rough  and  rocky,  here  smooth  and  pleasant,  up  hill 
and  down  dale,  dead  level  and  what  not,  it  all  seems  very  inter- 
esting and  mostly  satisfactory,  to  review  and  observe  the  testi- 
mony and  evidence  of  the  struggle  which  we  may  now  safely 
call  successful,  and  again  pause  and  endeavor  to  realize  the 
hard  work,  the  gropings  in  the  dark,  and  the  toiling  years  that 
have  gone  before. 


CHAPTER  II 

HISTORICAL 

HISTORY  repeats  itself.  The  earliest  written  history  in  which 
heat  takes  steam  for  a  vehicle  in  its  performance  of  work  by 
means  of  mechanism  made  by  human  beings,  sets  forth  the 
steam  turbine  driven  by  the  reaction  of  steam  jets.  This  was 
about  130  years  before  the  Christian  Era.  The  steam  turbine 
is  again  with  us.  But  whether  this  portion  of  the  cycle  of 
events  is  at  or  near  the  top,  or  at  or  near  the  bottom,  is  not 
yet  evident.  The  first  full  fledged  steam  turbine  driving  a 
water  turbine  so  as  to  form  a  turbine  pumping  engine  in  the 
real  sense  of  the  term,  and  of  a  capacity  and  importance  suffi- 
cient to  establish  its  status  in  the  water  works  field,  is  yet  to 
come.  The  steam  turbine  and  the  water  turbine  have  their 
proper  fields  of  usefulness  no  doubt,  but  they  have  not  been 
clearly  defined. 

There  are  in  this  country  and  in  Europe  eminent  and  highly 
successful  engineers  who  predict  that  the  steam  turbine  will 
go  into  hiding  again  within  ten  years.  They  are  no  doubt 
sincere  in  their  convictions,  but  they  may  be  mistaken  or  preju- 
diced against  the  turbine,  although  the  even  balance  in  which 
they  have  heretofore  held  the  scales  of  investigation  place  them 
high  up  in  their  profession,  and  they  have  no  special  interest 
in  giving  an  adverse  judgment. 

Fig.  1  shows  a  picture  of  Hero's  steam  turbine  which  as  will 
be  readily  seen  was  of  the  reactionary  class,  and  evidently 
would  not  rank  very  high  in  the  scale  of  economy. 

In  1601  the  raising  of  water  by  steam  power,  by  condens- 
ing the  steam  within  a  closed  vessel  was  known  and  the  fact 
published.  The  idea  is  that  the  vessel  being  connected  by 

8 


HISTORICAL 


means  of  a  suitable  pipe  with  a  body  of  water,  the  admission 
of  steam  into  an  air  tight  vessel  would  drive  out  the  atmos- 
pheric air,  and  then  upon  the  condensation  of  the  steam,  the 
supply  being  shut  off,  a  vacuum  or  a  partial  vacuum  being 
produced,  the  water  would  ascend  the  pipe  and  fill  the  vessel. 

In  1615  the  idea  was  known  of  sending  a  jet  of  water  to  a 
great  height  by  means  of  steam  pressure  acting  directly  upon 
the  surface  of  the  water,  within  a 
closed   vessel    provided    with    an 
outlet  pipe  for  the  ejection  of  the 
water. 

In  1629  it  was  well  known  that 
the  impulse  of  steam  against  vanes 
attached  to  a  wheel,  would  develop 
motion  and  power,  which  is  of 
course  further  evidence  of  the 
steam  turbine  idea  1759  years 
after  the  Hero  device. 

In  1656,  or  as  some  records  have 
it,  1663,  there  was  described  a 
machine  for  raising  water  by  steam 
pressure,  and  so  far  as  the  record 
can  be  interpreted  this  is  the  first 
attempt  to  raise  water  by  steam 
pressure  when  the  steam  was  gen- 
erated in  and  supplied  from  a  vessel  separate  from  the  vessel 
in  which  the  water  was  raised.  This  marks  the  birth  of  the 
pumping  plant  microbe  so  to  speak,  in  which  a  separate 
"boiler"  was  employed  to  generate  the  steam,  and  separate 
vessels  or  chambers  used  to  manipulate  the  water  to  be  raised. 
Thus  the  water  works  pumping  plant  as  now  used  in  principle, 
has  its  age  revealed;  taking  the  earlier  date,  this  is  250  years. 
.  The  Savery  pumping  engine  with  a  date  of  1697  seems  to  be 
the  first  one  in  which  it  was  attempted  to  "lift"  water  by  what 
we  now  call  "suction"  and  in  the  same  machine  also  lift  or 
"force"  the  water  to  a  considerable  height  above  the  engine. 


Fig.  1.  —  Hero's  Steam  Engine. 


10 


PUMPING  ENGINES 


So  that  the  pumping  engine  as  a  "lifting"  and  a  "forcing" 
machine  combined,  is  only  about  200  years  old,  or  209  accord- 
ing to  the  recorded  dates.  The  Savery  pumping  engine  gave 
a  practical  impetus  to  the  hydraulic  idea  of  raising  water  under 
pressure,  and  was  very  usefully  employed  for  mine  pumping 
upon  what  at  that  time  must  have  been  a  liberal  scale. 

Fig.  2  shows  a  sectional  picture  of  the  Savery  pumping 
engine,  which  gives  a  very  clear  idea  of  this  early  machine. 

In  the  pumping  machinery  up  to  and  including  the  Savery 


Fig.  2.  —  Savery' s  Pumping  Engine. 

engine,  the  steam  acted  mostly  by  its  pressure  directly  upon 
the  surface  of  the  water  and  without  the  intervention  of  pistons 
and  other  communicating  mechanism,  as  shown  in  the  most 
advanced  development  of  the  Savery  engine  in  1697  indicated 
in  Fig.  2. 

But  in  1690  the  idea  of  the  piston,  now  so  well  known,  to 
communicate  the  power  and  motion  derived  from  the  steam, 
to  mechanism,  had  already  been  born,  and  the  record  gives 
Denis  Papin  credit  for  the  invention.  Papin  was  also  the 


HISTORICAL 


11 


inventor  of  the  safety  valve  for  steam  boilers,  now  considered 
absolutely  necessary  wherever  steam  is  used.  The  piston  in 
the  steam  cylinder  was  first  exhibited  in  a  model,  and  in  this 
model  the  water,  a  small  quantity,  was  placed  in  the  bottom  of 
a  vertical  cylinder,  the  piston  resting  upon  the  water.  The 
application  of  heat  beneath  the  cylinder  generated  steam  and 
drove  the  piston  to  the  top,  whence  by  the  condensation  of  the 
steam  and  the  formation  of  a  vacuum  thereby,  the  piston  was 
driven  down  again  to  the  bottom  of  the  cylinder  by  the  pres- 
sure of  the  atmosphere,  or  the  air  we  breathe;  the  air  as  many 
know  exerts  a  pressure  of  nearly  fifteen 
pounds  per  square  inch  against  the  sides  of 
any  air  tight  vessel  containing  a  vacuum, 
or  entire  absence  of  air  or  vapor.  From 
the  idea  of  the  cylinder  and  piston  there 
followed  the  further  ideas  of  driving  pumps 
and  rotative  machinery. 

Cawley,  Newcomen,   Savery,   and   others 
used   the  piston,    the   separate  boiler,  and 
surface  condenser,  and  so  designed  the  well 
known  mine  pumping  engine  operated  by 
atmospheric  pressure  as  in  the  Papin  model. 
To  aid  the  condensation  of  the  steam,  and 
make  the  engines  work  more  rapidly  and 
promptly,  the  initial  form  of  the  jet  condenser  was  introduced, 
by  injecting  cold  water  into  the  steam  cylinder  itself. 

Devices  for  making  the  engine  open  and  close  its  own  valves 
were  soon  introduced,  the  first  by  Humphrey  Potter;  and  then 
the  valves  and  valve  gear  were  improved  by  Brighton. 

Then  Leupold  came  along  in  1725  or  thereabouts,  with  higher 
steam  pressures,  so  improvement  followed  improvement,  by 
Smeaton  and  others,  until  by  1770  this  form  of  pumping  engine 
in  which  steam  was  applied  beneath  the  piston,  and  the  atmos- 
phere applied  on  top  of  the  piston,  first  one  and  then  the  other, 
became  fully  up  to  date  for  its  time,  the  state  of  the  machinist's 
art,  tools,  and  appliances  generally,  considered. 


Fig.  3.  —  Model  of 
Papin' s  Piston  Engine. 


12 


PUMPING  ENGINES 


The  following  figures  show  pictures  of  the  various  steam 
pumping  engines  with  their  dates  of  invention  or  existence: 

Fig,  2.  Savery's  pumping  engine,  1697. 

Fig.  3.  Model  of  Papin's  piston  engine,  1690. 

Fig.  4.  Newcomen's  pumping  engine,  1705. 

Fig.  5.  Leupold's  pumping  engine,  1725. 
Up  to  about  1770,  Smeaton  had  perfected  so  far  as  possible 
what  is  known  as  the  atmospheric  engine,  considering  the  uncer- 
tain and  unknown  lines  then  being  followed.     By  the  atmos- 
pheric engine  is  meant  the  engine  at  that  time  in  the  field,  in 


Newcomen's  Pumping  Engine. 


which  the  pressure  of  the  atmosphere  on  the  upper  surface  of 
the  piston  of  an  open  top  vertical  cylinder,  was  an  important 
element. 

In  1736  James  Watt  was  born,  and  in  1759  he  entered  the  field 
of  steam  engineering.  Up  to  the  advent  of  Watt  the  progress 
in  steam  engineering  had  been  confined  to  making  small  altera- 
tions in  specimens  then  in  existence,  and  with  very  limited  results. 
The  steam  engine  as  then  designed  and  constructed  represented 


HISTORICAL 


13 


rude  accomplishments,  a  very  large  amount  of  waste,  and  a 
very  small  measure  of  efficiency. 

When  Watt  came  in  contact  with  the  subject  of  steam,  he 
endeavored  to  grasp  it  broadly,  and  according  to  the  scientific 
lights  of  the  times.  In  fact  Watt  was  the  first  scientific  steam 
engineer,  and  made  a  very  great  success  of  the  matter.  He 
struck  out  on  broad  principles,  instead  of  narrowly  following 


Fig.  5, — Leupold's  Pumping  Engine. 

precedents  and  the  then  existing  examples.  He  dealt  with 
principles  instead  of  details,  and  the  details  soon  suggested 
themselves.  He  determined  from  what  he  could  learn  from 
the  nature  and  action  of  steam,  that  the  steam  cylinder  in  which 
the  steam  did  the  work,  must  be  kept  HOT  ;  and  that  a  condenser, 
which  he  had  introduced  as  a  complete  and  separate  vessel  from 
the  steam  cylinder,  must  be  kept  COOL.  And  in  carrying  out 
these  underlying  principles  he  introduced  a  steam  jacket,  and 


14  PUMPING  ENGINES 

the  separate  condenser,  which  are  used  to  this  day.  With 
Watt  also  came  the  cutting  off  of  the  steam  within  the  cylinder 
before  the  stroke  was  finished,  early  or  late  according  to  condi- 
tions, and  the  completion  of  the  piston's  stroke  by  the  expan- 
sion of  the  steam  within  the  cylinder  independently  of  the  boilers. 
Also  the  double  action  engine  with  its  closed  cylinder  top  and 
a  stuffing  box  for  the  piston  rod  to  work  through,  and  with 
steam  driving  the  piston  throughout  both  strokes. 

The  use  of  the  crank  which  we  now  know  so  well  in  all  sorts  of 
machines  aside  from  the  steam  engine  itself,  was  introduced 
about  this  time  to  produce  rotative  motion  of  a  shaft  from  the 
reciprocating  motion  of  a  piston,  and  its  invention  was  disputed 
between  Watt  and  Pickard,  the  latter  however  obtaining  suffi- 
cient advantage  in  the  controversy  to  obtain  a  patent  on  the 
crank,  thus  compelling  Watt  to  use  the  device  known  as  the 
"Sun  and  Planet"  motion  until  the  patent  on  the  crank  had 
expired.  The  crank  was  the  better,  in  fact  the  best  of  all  devices 
for  the  purpose,  and  was  adopted  and  used  by  all  steam  engine 
builders  where  rotary  motion  was  desired.  Watt  had  made 
most  of  his  inventions  of  the  above  mentioned  details,  together 
with  some  minor  ones,  by  1784,  including  the  parallel  motion 
for  conveying  the  straight  piston  rod  motion  to  the  vibrating 
end  of  the  working  beam;  the  governor  for  regulating  speed; 
and  the  steam  engine  indicator. 

In  1769  Watt  wrote  a  specification  to  cover  his  inventions 
and  researches,  and  the  writer  considers  them  of  sufficient  his- 
torical interest  to  give  them  here  in  full,  aside  from  the  fact 
that  to  this  day  this  specification  embodies  the  principles  which 
the  scientific  development  of  the  steam  engine  are  based  upon. 
Watt's  specification,  with  the  language  slightly  changed  in 
places  to  suit  the  present  time,  is  as  follows: 

First:  That  vessel  in  which  the  powers  of  steam  are  to  be 
employed  to  work  the  engine,  which  is  called  the  cylinder  in 
common  engines,  and  which  I  call  the  steam  vessel,  must  during 
the  whole  time  the  engine  is  at  work,  be  kept  as  hot  as  the  steam 
which  enters  it;  first  by  enclosing  it  in  a  case  of  wood,  or  any 


HISTORICAL  15 

other  materials  which  transmit  heat  slowly;  secondly,  by  sur- 
rounding it  with  steam  or  other  heated  bodies;  and,  thirdly,  by 
suffering  neither  water  nor  any  other  substance  colder  than  the 
steam  to  enter  or  touch  it  during  that  time. 

Secondly:  In  engines  that  are  to  be  worked  wholly  or  partially 
by  condensation  of  steam,  the  steam  is  to  be  condensed  in  vessels 
distinct  from  the  steam  vessels  or  cylinders,  although  occasionally 
communicating  with  them;  these  vessels  I  call  condensers;  and, 
whilst  the  engines  are  working,  these  condensers  ought  at  least 
to  be  kept  as  cold  as  the  air  in  the  neighborhood  of  the  engines, 
by  the  application  of  water  or  other  cold  bodies. 

Thirdly:  Whatever  air  or  other  elastic  vapor  is  not  condensed 
by  the  cold  of  the  condenser,  and  may  impede  the  working  of 
the  engine,  is  to  be  drawn  out  of  the  steam  vessels  or  condensers 
by  means  of  pumps,  wrought  by  the  engines  themselves  or 
otherwise. 

Fourthly:  I  intend  in  many  cases  to  employ  the  expansive 
force  of  steam  to  press  on  the  pistons,  or  whatever  may  be  used 
instead  of  them,  in  the  manner  in  which  the  pressure  of  the 
atmosphere  is  now  employed  in  common  engines.  In  cases 
where  cold  water  cannot  be  had  in  plenty,  the  engines  may  be 
wrought  by  this  force  of  steam  only,  by  discharging  the  steam 
into  the  air  after  it  has  done  its  office. 

Fifthly:  ******  Rotary  engine. 

Sixthly:  I  intend  in  some  cases  to  apply  a  degree  of  cold  not 
capable  of  reducing  the  steam  to  water,  but  of  contracting  it 
considerably  so  that  the  engine  shall  be  worked  by  the  alternate 
expansion  and  contraction  of  the  steam. 

Lastly:  Instead  of  using  water  to  render  the  pistons  and  other 
parts  of  the  engine  air  and  steam  tight,  I  employ  oils,  wax,  resin- 
ous bodies,  fat  of  animals,  quick  silver  and  other  metals  in  their 
fluid  state. 

Contemporary  with  James  Watt,  there  lived  Jonathan  Horn- 
blower,  who  in  1781  invented  and  patented  the  double  cylinder 
or  compound  engine  with  two  cylinders  of  different  diameters 
and  in  some  cases  with  different  lengths  of  stroke.  Steam 


16  PUMPING  ENGINES 

was  admitted  as  at  the  present  time  into  the  smaller  cylinder, 
and  after  doing  work  there  was  exhausted  over  into  the  larger 
cylinder  and  was  again  employed  against  the  second  piston. 
Hornblower  soon  found;  especially  in  those  days  of  compara- 
tively low  steam  pressure,  that  the  use  of  a  separate  condenser 
was  necessary  to  the  success  of  his  engine,  and  this  threw  him 
into  antagonism  with  Watt,  practically  placing  a  fatal  obstacle 
in  his  path. 

In  1804  Woolf  again  brought  forward  the  compound  steam 
engine,  and  although  it  was  essentially  the  same  in  principle  as 
Hornblower's  invention,  it  often  bears  the  name  of  Woolf  to 
the  exclusion  of  that  of  its  real  inventor.  Woolf  employed 
what  was  then  considered  high  steam  pressure  and  cut  off  in 
the  smaller  cylinder,  beginning  the  expansion  in  that  cylinder 
and  continuing  it  throughout  the  full  stroke  of  the  larger  cylin- 
der, a  plan  of  operation  extensively  used  with  pumping  engines 
during  the  past  twenty  years.  The  application  of  Watt's  con- 
denser to  the  so-called  Woolf  compound  engine,  marked  a  step 
forward  which  has  lasted  even  into  the  present  day,  and  is 
regarded  as  the  only  material  improvement  of  importance  since 
the  improvements  of  Watt.  The  economy  of  the  compound 
engine  was  clear  enough  at  the  time  of  its  introduction  and  up 
to  1814  it  came  along  rapidly,  but  the  steam  pressures  of  that 
day  were  too  low  to  enable  it  to  compete  with  the  single  cylinder 
Cornish  engine  carrying  an  equally  high  pressure,  and  cutting 
off  at  an  early  point  in  the  stroke,  which  the  Cornish  engine  of 
Trevithick  was  enabled  to  accomplish  by  virtue  of  the  massive 
pump  rods  then  used  in  connection  with  the  deep  mine  pumps. 
What  is  undoubtedly  the  chief  advantage  of  compounding,  or  the 
use  of  multiple  cylinders,  was  not  thought  of  for  many  years 
after  the  invention  of  this  form  of  the  steam  engine,  and  in  fact 
was  probably  hidden  on  account  of  the  limited  steam  pressures 
employed.  That  is  the  limiting  of  the  range  of  temperature 
in  any  one  cylinder. 

In  1845  the  compound  idea  was  again  brought  to  the  front  by 
McNaught,  for  the  purpose  of  gaining  power  where  it  was  not 


HISTORICAL 


17 


convenient  to  put  in  a  newer  and  larger  engine.  A  higher  steam 
pressure  was  used  for  the  reason  that  it  was  no  doubt  seen  that 
to  gain  anything  with  the  additional  cylinder  this  smaller  cylin- 
der must  have  available  for  its  piston,  a  steam  pressure  some- 
what above  that  formerly  employed  in  the  old  and  larger  cylinder 
exhausting  into  the  condenser.  The  additional  power  was 


Fig.  6,— Watt's  Engine,  1769. 

obtained  from  the  new  high  pressure  cylinder,  and  the  steam 
rejected  by  it  was  utilized  by  the  low  pressure  cylinder,  leaving 
the  latter  about  under  the  conditions  as  formerly.  After  this 
original  McNaught  experiment  was  found  to  be  successful,  other 
engines  were  improved  in  the  same  way,  and  it  was  found  that 
not  only  was  power  gained  due  to  the  actual  additions  to  pistons 
and  pressures,  but  a  distinct  gain  in  economy  of  steam  and  fuel 
resulted  as  well. 


OF  THE 

UNIVERSITY 


18  PUMPING  ENGINES 

In  1850  the  compound  engine  appeared  as  a  water  works 
pumping  engine  at  the  Lambeth  and  other  water  works  plants. 
In  1854  it  went  into  marine  practice;  and  in  1857  the  receiver 
between  the  high  and  low  pressure  cylinders  was  introduced 
with  reheating  facilities,  thus  departing  from  the  Hornblower- 
Woolf  alternating  pistons,  and  opening  the  way  for  pumping 
and  other  engines,  with  cranks  at  90°  and  at  120°  as  we  find  in  the 
latest  modern  practice. 

So  it  will  be  seen  that  124  years  ago  most  of  the  elements  now 
employed  in  pumping  engines  of  the  highest  class  were  known 
-and  used,  and  are  as  follows: 

Steam  working  on  both  sides  of  the  piston. 

Higher  and  higher  steam  pressures. 

Non-rotative  pumping  engines. 

Crank  and  fly  wheel  pumping  engines. 

Steam  jackets. 

Cut  off  and  expansion  of  steam  within  the  cyliiuler. 

Compound  engines. 

Surface  condensers. 

Separate  jet  condensers  with  air  pump. 

Poppet  steam  valves. 

Ball  governors. 

Throttle  valve. 

Steam  engine  indicator. 

Parallel  motion  for  crossheads. 

Crosshead  and  guides. 

Revolution  counter. 

Three  of  Watt's  engines,  exhibiting  the  advance  in  his  work 
are  shown  in  the  following  pictures: 

Fig.  6.  Watt's  engine  of  1769. 

Fig.  7.  Watt's  engine  of  1781. 

Fig.  8.  Watt's  engine  of  1784. 

.  A  deeper  scientific  knowledge  of  heat  and  steam,  together 
with  better  tools  and  improved  materials,  have  combined  to 
refine  the  steam  engine  and  the  water  works  pump,  greatly 
increasing  their  economical  efficiency;  but  after  all  James  Watt 


HISTORICAL  19 

turned  out  a  complete  machine  for  the  purpose  in  view  as  the 
above  list  of  details  employed  even  at  the  present  time  will  testify. 
And  to  show  how  fully  his  qualities  were  recognized  and  appre- 
ciated we  have  only  to  note  that  a  monument  was  placed  in  that 
most  exclusive  of  precincts,  Westminster  Abbey,  inscribed 
as  follows : 


Not  to  perpetuate  a  Name, 
Which  must  endure  while  the  peaceful  arts  flourish,  but 

to  show 

that  mankind  have  learnt  to  honor  those 
who  best  deserve  their  gratitude, 

THE  KING. 
his  ministers,  and  many  of  the  nobles  and  commoners  of 

the  realm, 
raised  this  monument  to 

JAMES    WATT, 

Who,  directing  the  force  of  an  original  genius, 
early  exercised  in  philosophic  research, 

to  the  improvement  of 
THE  STEAM  ENGINE, 

enlarged  the  resources  of  his  country,  increased  the 
power  of  man,  and  rose  to  an  eminent  place 

among  the  most  illustrious  followers 
of  science  and  the  real  benefactors  of  the  world. 

Born  at  Greenock,  MDCCXXXVI. 
Died  at  Heathfield,  in  Staffordshire,  MDCCCXIX. 


There  was  very  little  indeed  in  the  line  of  theory  to  influence 
or  guide  the  early  inventors  of  the  steam  engine.  Watt  had 
some  advantages  through  his  associations  at  the  Glasgow  Univer- 
sity, with  reference  to  the  doctrine  of  latent  heat,  but  the  rela- 
tion of  work  to  heat  was  not  developed  into  a  philosophical 
proposition  until  a  considerable  time  a'fter  Watt's  inventions 
and  determinations.  It  was  after  Watt's  death  that  Carnot 
in  1824  published  the  theory  of  the  steam  engine  as  a  heat  engine, 
and  demonstrated  that  heat  does  work  only  by  being  let  down 


20 


PUMPING  ENGINES 


from  a  higher  to  a  lower  level,  but  even  he  had  not  grasped  the 
full  idea  of  the  relation  of  heat  to  work,  and  it  remained  for  Joule 
in  1843  to  demonstrate  the  conservation  or  convertibility  of 
energy  by  showing  conclusively  that  heat  and  work  were  inter- 
convertible one  into  the  other,  he  then  setting  a  standard  that  the 
equivalent  of  one  unit  of  heat  in  mechanical  energy  is  772  pounds 


Fig.  7. —Watt's  Engine,  1781. 

raised  or  lifted  to  a  height  of  one  foot,  a  standard  which  is  still 
recognized;  and  one  unit  of  heat  is  that  amount  of  heat  which 
will  raise  one  pound  of  water  one  degree  by  the  Fahrenheit 
thermometer,  or  the  thermometer  we  are  used  to  seeing  every 
day,  from  temperature  39  to  temperature  40,  at  which  tempera- 
ture water  is  supposed  to  attain  its  greatest  density.  From 
1849  the  science  of  heat  energy  made  great  strides  and  was  set 
forth  by  the  most  profound  philosophers  and  mathematicians 
of  our  times. 


HISTORICAL 


21 


The  theory  of  heat  engines  taken  from  competent  authorities 
may  be  briefly  stated  as  follows : 

A  heat  engine  acts  by  taking  in  heat,  converting  a  part  of  the 
heat  received  into  mechanical  energy,  which  appears  as  the  work 
done  by  the  engine,  and  rejecting  the  remainder,  still  in  the  form 
of  heat.  The  theory  of  heat  engines  comprises  the  study  of  the 
amount  of  work  done,  in  its  relation  to  the  heat  applied  and  ta 


Fig.  8.  — Watt's  Engine,  1784. 

the  heat  rejected.  The  theory  is  based  on  the  two  laws  of  ther- 
modynamics or  heat  energy,  which  may  be  stated  as  follows  : 

LAW  I.  When  mechanical  energy  is  produced  from  heat,  one 
thermal  unit  of  heat  goes  out  of  existence  for  every  772  foot 
pounds  of  work  done ;  and,  conversely,  when  heat  is  produced  by 
the  expenditure  of  mechanical  energy,  one  thermal  unit  of  heat 
comes  into  existence  for  every  772  foot  pounds  of  work  spent. 

LAW  II.  It  is  impossible  for  a  self-acting  machine,  unaided 
by  any  external  energy,  to  convey  heat  from  one  body  to  another 
at  a  higher  temperature. 


CHAPTER  III 

ECONOMIC  STEAM   DUTY 

THE  highest  economic  duty  in  proportion  to  first  cost  and 
maintenance  determines  the  most  desirable  pumping  engine. 
And  ever  since  the  early  days  of  Newcomen  and  Watt  there  has 
been  a  continual  advance  in  design,  construction,  and  perform- 
ance as  expressed  in  economic  "duty"  of  pumping  engines, 
accompanied  by  a  reasonable  measure  of  durability  in  the 
machine,  as  the  physical  conditions  imposed  became  more  and 
more  understood.  The  increase  in  the  number  of  opportunities 
for  usefully  employing  the  energy  of  heat,  and  the  decrease  in 
the  chances  for  wastefulness  from  purely  mechanical  defects, 
have  contributed  very  effectually  towards  the  improvement 
from  5,000,000  foot  pounds  duty  hi  the  old  time  Savery  engines^ 
upwards  to  the  12,000,000  duty  mark  of  Smeaton  and  New- 
comen; then  to  the  20,000,000  duty  of  Watt's  engines,  then  to 
the  30,000,000,  then  to  60,000,000  duty,  as  the  later  achieve- 
ments of  the  Cornish  engine  came  into  the  record.  And  so  on 
up  to  80,000,000  duty,  until  finally  in  the  latter  half  of  the  nine- 
teenth century,  after  say  1860,  the  higher  steam  pressures  and  the 
higher  ratios  of  steam  expansion  carried  the  duties  of  the  pump- 
ing engine  up  to  past  the  100,000,000  the  110,000,000  and  the 
120,000,000  duty  marks  successively;  finally  reaching  very 
nearly  to  the  possible  limits  to-day,  a  little  over  181,000,000  foot 
pounds  of  work  per  1,000  pounds  weight  of  dry  saturated  steam 
consumed;  that  is,  steam  theoretically  perfect,  containing  the 
exact  amount  of  water  and  heat  which  carefully  made  experi- 
ments have  determined  to  be  correct  according  to  natural  laws. 

The  record  at  present,  as  exhibited  by  the  pumping  engines 
produced  in  this  country  at  least,  and  covering  the  practice  of  a 

22 


ECONOMIC  STEAM  DUTY 


23 


goodly  number  of  designers,  in  fact  the  principle  engineers  in 
this  line  both  for  special  designs  and  for  what  might  be  termed 
commercial  machines,  is  given  in  the  following  table : 

Present   Day  Duty  Record  per    1,000  pounds   of  Dry  Saturated   Steam. 


BUILDER  OK  DESIGNER. 

DUTY   IN   FOOT  POUNDS. 

Allis-Chalmers  Company     
Edw.  P.  Allis  Company  
Holly  Manufacturing  Company  
Snow  Steam  Pump  Company     
E.  D.  Leavitt 

181,068,605 
179,454,250 
173,620,000 
167,800,000 
157  843  000 

Lake  Erie  Engineering  Works        
Nordberg  Manufacturing  Company  

152,000,000 
149,500,000 

The  following  is  the  pumping  record  for  duty  with  superheated 
steam  as  taken  from  some  tests  at  Chicago,  of  Worthington 
vertical  triple  expansion  engines  of  20,000,000  U.  S.  gallons 
daily  capacity  each : 


Average  superheat. 
100° 

Greatest  superheat. 
154° 

Average  steam  pressure. 
144  Ibs.  gauge. 

Greatest  steam  pressure. 
147  Ibs.  gauge. 

Duty. 
161,718,936  ft.  Ibs. 

Duty. 
174,735,801  ft.  Ibs. 

At  the  close  of  the  year  1905,  the  pumping  engine  hold- 
ing the  world's  record  for  general  economy,  was  at  Boston, 
Mass.,  U.S.A.,  in  the  high  service  station  of  that  city  at  Chest- 
nut Hill  pumping  station.  The  data  of  this  engine  are  as 
follows : 

Designers,  E.  &  I.  H.  Reynolds. 

Builders,  Edward  P.  Allis  Company. 

Date  of  completion,  1897. 

Location,  Boston  High  Service. 

Capacity  per  24  hours,  U.  S.  standard,  30,000,000  gallons. 

Total  head  against  plungers,  140  feet. 

Steam  pressure  per  gauge,  185  Ibs. 


24  PUMPING  ENGINES 

Duty  per  1,000  Ibs.  dry  saturated  steam,  178,497,000  ft.  Ibs. 
Duty  per  1,000,000  British  thermal  units,  163,925,000  ft.  Ibs. 
Steam  per  indicated  horse  power  hour,  10.335  Ibs. 
British  thermal  units  per  indicated  horsepower  minute,  187.8. 
Thermal  efficiency  from  absolute  zero,  21.63  per  cent. 
The  indicated  horse  power  of  this  engine  is  802  under  the  above 
conditions,  and  the  pump  horse  power,  748,  giving  a  mechanical 
efficiency  of  about  93.3  per  cent.     The  steam  was  supplied  by 
one  large  boiler  of  special  design  of  the  locomotive  type,  and 
was  fitted  with  economizers  in  the  back  flue  built  for  the  purpose. 
The  actual  evaporation  in  the  boiler  under  working  conditions 
and  pressure  when  using  the  economizer,  per  pound  of  dry  coal 
was  10.472  Ibs.  and  the  efficiency  of  the  boiler  when  using  the 
economizers  was  86  per  cent. 

Duty  of  engine  per  100  Ibs.  of  coal,  173,869,000  ft.  Ibs. 
Coal  per  indicated  horse  power  hour,  1.062  Ibs. 
The  average  duty  per  1,000  Ibs.  of  dry  saturated  steam,  which 
is  steam  without  either  moisture  or  superheat,  as  given  by  26  of 
the  highest  type  and  class  of  American  pumping  engines  up  to 
January  1,  1906,  is  162,900,000  foot  pounds.     The  builders  and 
designers  include  the  following  well  known  names : 
Edward  P.  Allis  Company. 
Henry  R.  Worthington. 
E.  D.  Leavitt  (designer  only). 
Holly  Manufacturing  Company. 
Lake  Erie  Engineering  Works. 
Snow  Steam  Pump  Works. 
Nordberg  Manufacturing  Company. 
Allis-Chalmers  Company. 

The  principal  improvement  in  the  line  of  economy  in  the  use 
of  heat  energy  as  furnished  by  steam  in  pumping  engines,  has 
been  brought  about  by  a  better  understanding  of  heat  and  the 
heat  engine,  of  the  treatment  and  manipulation  of  the  working 
steam  within  the  engine  cylinders,  and  by  the  steady  increase 
in  the  steam  pressures  employed.  This  increase  in  steam  pres- 


ECONOMIC  STEAM  DUTY 


25 


•sures  may  be  quickly  comprehended  at  a  glance  by  observing 
the  following  table : 


STEAM  PRESSURE  IN 

POUNDS 

PER 

GAUGE. 

1800 

5 

1830   .  .  .  '. 

20 

1850   .... 

50 

1875  .... 

75 

1900  .... 

125 

1906   .... 

175 

Again,  as  the  pressure  of  steam  gradually  increased,  its  logical 
accompaniment,  the  increase  in  the  ratio  or  rate  of  expansion 
took  its  proper  place  in  the  march  of  improvement.  The  users 
of  steam  began  by  taking  it  within  the  cylinders  of  the  early 
engines  during  the  entire  stroke  of  the  piston,  in  those  first  days 
of  the  steam  engine,  after  Papin  had  suggested  and  demon- 
strated the  idea  and  possibility  of  the  piston.  Then  four  expan- 
sions were  employed  in  the  Watt,  and  also  in  the  Trevithick 
Cornish  engines  used  for  pumping  out  mines,  from  1814  to  1824, 
the  records  even  giving  so  high  a  pressure  as  120  Ibs.  per  square 
inch.  But  such  a  pressure  in  the  light  of  what  must  have  been 
the  limited  scope  of  steam  boilers  at  that  time,  is  at  least  ques- 
tionable; and,  besides  it  is  said  that  Woolf's  compound  engine 
was  kept  out  of  business  on  account  of  the  greater  simplicity  of 
the  single  cylinder  Trevithick  engine  at  the  Cornwall  mines,  and 
such  a  statement  is  at  least  improbable  if  120  Ibs.  pressure  was 
employed,  for  the  reason  that  whether  the  lessening  of  the  range 
of  temperature  brought  about  by  the  use  of  two  cylinders  was 
understood  or  not,  the  inevitable  and  natural  effect  of  reducing 
the  coal  consumption  for  the  work  done  would  have  been  plainly 
visible  evan  though  the  relations  between  heat,  steam,  and 
energy,  were  still  unknown. 

As  later  perfections  in  engines  came  into  existence,  the  rate 
of  expansion  gradually  increased  with  the  steam  pressure,  and 
went  successively  to  6,  8,  10,  12,  16,  20,  and  upwards  to  the  pres- 


26  PUMPING  ENGINES 

ent  day  limit.  About  5  Ibs.  absolute  pressure,  or,  5  Ibs.  above 
a  perfect  vacuum  seems  to  be  the  low  limit  of  terminal  pressure 
of  profitable  expansion  and  practical  conditions;  and  with  suffi- 
cient protection  against  condensation  within  the  cylinder,  it  is 
doubtful  if  a  lower  pressure  than  this  can  be  obtained  in  the 
absence  of  leakage.  Indeed  it  is  extremely  difficult  to  get  the 
expansion  in  proper  form  down  to  so  low  a  point  as  5  Ibs.  above 
perfect  vacuum.  It  is  very  difficult  if  not  impossible  to  provide 
latent  heat  enough  and  to  supply  it  quickly  enough  within  the 
cylinder,  to  obtain  perfectly  dry  initial  steam  or  to  maintain 
perfect  evaporation  without  incurring  losses  in  other  directions; 
but  the  slower  the  strokes  of  the  engine,  the  better  the  chances 
of  ideal  steam  conditions;  and  this  probably  explains  the  high 
efficiency  of  the  slow  moving  pumping  engines,  the  type  of  steam 
machinery  holding  the  record  for  low  steam  consumption  and 
high  heat  efficiency.  Perhaps  the  rate  of  speed  could  be  brought 
down  until  there  would  be  time  enough  in  each  stroke  to  begin 
the  superheating  of  the  low  pressure  exhaust,  and  if  this  did  not 
raise  the  capital  account  too  high  by  unduly  enlarging  the  engine, 
the  complete  dryness  of  the  low  pressure  exhaust  just  to  the 
point  of  saturation  would  likely  mark  the  most  profitable  rate 
of  motion  in  pumping  engines,  especially  so  when  it  is  considered 
that  the  highest  mechanical  efficiency  of  machines  lies  in  this 
direction. 

But  the  great  effect  to  be  obtained  within  a  steam  cylinder 
is  perfect  dryness  of  the  initial  steam.  If  this  can  be  accom- 
plished the  rest  of  the  stroke  will  take  care  of  itself,  and  if  it  was 
or  ever  is  found  that  initial  dryness  will  result  in  superheated 
exhaust  especially  in  the  low  pressure  cylinder,  the  quality  of 
the  steam  must  be  controlled  so  that  the  best  practical  point 
can  be  reached  for  all  around  results.  Dry  initial  steam  in  the 
low  pressure  cylinder  has  not  yet  been  reached,  the  nearest 
approach  being  something  like  9  per  cent  moisture  remaining, 
but  the  economic  duty  is  at  present  so  high  that  the  small  mar- 
gin yet  to  be  attained  will  not  stand  very  much  expense  for  its 
acquisition. 


ECONOMIC  STEAM  DUTY 


27 


Upon  the  basis  of  5  Ibs.  absolute  terminal  pressure,  that  is, 
5  Ibs.  above  perfect  vacuum,  the  possible  ideal  ratios  of  expan- 
sion in  the  absence  of  the  usual  disturbing  conditions  would  be 
as  follows  with  various  steam  pressures  per  gauge : 


STEAM  PRESSURE 
PER  GAUGE. 

EXPANSIONS. 

STEAM  PRESSURES 
PER  GAUGE. 

EXPANSIONS. 

5 

4 

75 

18 

10 

5 

100 

25 

25 

8 

125 

28 

40 

11 

150 

33 

50 

13 

175 

38 

60 

15 

200 

43 

Thus  will  be  seen  to  some  extent  the  fallacy  in  seeking  greater 
economy  in  more  rapid  motion  of  the  piston  and  rotative  parts. 
Aside  from  the  lessening  of  the  mechanical  efficiency  of  the 
machine,  by  disturbances  in  the  main  pumps  and  increased 
friction  in  other  directions,  the  cooling  due  to  the  expansion 
of  the  steam,  and  the  ranges  of  temperature  within  the  cylinders, 
all  due  to  the  expanding  steam  itself,  and  the  very  slight  com- 
parative change  in  the  time  for  such  operations,  in  a  fast  or  a 
slow  moving  engine,  as  usually  understood,  go  for  nothing.  As 
will  hereafter  be  pointed  out  in  connection  with  the  adaption  of 
pumping  engines  to  their  surrounding,  the  singled  out  factors 
of  high  steam  pressure,  high  rotative  speed,  high  piston  speed, 
and  similar  factors,  taken  by  themselves  in  the  absence  of  the 
really  controlling  conditions,  fail  to  advance  the  efficiency  of 
pumping  engines. 

The  original  Cornish  pumping  engine  was  a  beam  engine,  with 
the  steam  piston  connected  to  one  end  of  the  beam  and  a  rather 
massive  pump  rod  at  the  other  end  of  the  beam.  The  cut  off  of 
the  steam  took  place  at  an  early  point  of  the  stroke,  and  then 
the  stroke  was  finished  by  the  expanding  steam  and  the  momen- 
tum of  the  heavy  moving  parts.  This  was  for  mine  pumping 
and  counterbalancing  was  sometimes  resorted  to  when  the  pump 
rods  overweighted  the  beam  at  one  end.  When  this  engine  was 
introduced  into  municipal  water  supply  pumping,  in  the  absence 


28  PUMPING  ENGINES 

of  long  heavy  pump  rods  in  engine  house  work,  heavy  weights 
were  added  to  make  up  the  opportunity  for  storing  energy  which 
was  originally  furnished  by  the  long  pump  rods  necessary  hi 
mine  pumping. 

The  "Bull"  Cornish  pumping  engine,  the  advance  agent  so 
to  speak  of  the  modern  "direct  acting"  pump,  was  a  modifica- 
tion of  the  original  Cornish  engine,  and  in  this  machine  the  beam 
was  omitted,  aside  from  a  balancing  beam  when  the  rod  weights 
were  too  heavy  for  satisfactory  operation. 

The  economic  duty  of  the  Cornish  engine  has  been  given  in 
times  past,  ranging  from  30,000,000  in  1820  through  the  suc- 
ceeding years  up  to  114,000,000  in  1850,  per  100  Ibs.  of  coal, 
although  nothing  particular  is  said  about  the  efficiency  of  the 
boilers,  and  of  course  when  duty  is  given  in  pounds  of  coal 
burned,  the  efficiency  of  the  grates,  the  chimney,  the  quality 
of  the  coal,  and  the  generating  or  steam  making  power  of  the 
boilers,  become  involved  in  the  question.  It  must  be  obvious 
that  the  engine  cannot  possibly  be  responsible  for  the  cost  of 
the  making  of  the  steam,  although  the  "coal  duty"  of  an  engine 
is  often  talked  about,  this  term  really  meaning  the  "  plant  duty. " 
The  engine  has  no  grates  and  burns  no  coal,  but  the  engine  is 
responsible  for  the  amount  of  steam  used  in  doing  any  certain 
amount  of  work,  this  steam  furnished  by  the  boiler,  which  does 
have  grates,  and  upon  which  and  for  the  use  of  the  boiler,  the 
coal  is  burned.  This  consideration  has  finally  brought  about 
the  expression  of  the  duty  of  a  pumping  engine  per  1,000  Ibs. 
of  steam,  and  also  per  1,000,000  heat  units;  the  rate  of  a  thou- 
sand pounds  of  steam,  and  the  million  heat  units  coming  natu- 
rally enough  from  the  idea  of  a  hundred  pounds  of  coal,  giving 
an  evaporation  in  the  boilers  of  10  Ibs.  of  steam  for  each  pound 
of  coal  burned  on  the  boiler  grates.  That  is  to  say,  10  Ibs.  of 
water  evaporated  into  steam  per  pound  of  coal  burned  on  the 
grates,  is  equal  to  100  Ibs.  of  coal  evaporating  1,000  Ibs.  of  water 
into  steam.  From  a  scientific  point  of  view,  and  for  the  guidance 
of  the  engine  designer  and  builder,  the  expression  of  duty  per 
1,000,000  heat  units  usually  called  British  thermal  units  may 


ECONOMIC  STEAM  DUTY  29 

be  the  better  and  no  doubt  is,  but  for  the  buyer  of  the  engine, 
and  the  buyer  of  the  coal,  the  expression  in  terms  of  1,000  Ibs. 
of  steam  is  in  the  opinion  of  the  writer  the  better;  and  for  the 
reason  that  the  economies  of  the  boiler  room,  the  looking  after 
all  possible  raising  of  the  temperature  of  the  feed  water,  the 
most  advantageous  mode  of  firing  the  boilers,  and  everything 
in  fact  but  the  actual  using  of  the  steam  by  the  engine,  naturally 
separates  from  the  operation  of  the  machinery ;  and  the  consump- 
tion of  the  steam  whether  it  is  made  from  ice  cold  water  or  from 
very  hot  water,  is  an  extremely  satisfactory  way  to  measure  the 
performance  of  the  steam  cylinders.  The  idea  is  to  make  the 
steam  to  the  best  advantage  possible  and  then  get  the  most 
work  out  of  it  after  it  is  delivered  to  the  engine. 

Up  to  1848,  although  the  Watt  crank  and  fly  wheel  engine 
had  been  in  existence  a  good  many  years,  it  does  not  seem  to 
have  been  utilized  as  a  pumping  engine  to  any  very  great  extent; 
but  in  that  year  there  was  brought  out  in  London,  England, 
the  Simpson  compound  beam  pumrjing  engine,  with  the  bucket- 
plunger  pump,  and  for  25  years'was  considered  the  standard 
pumping  engine  for  considerable  quantities  of  water,  say,  from 
5,000,000  gallons  daily  upwards.  Fig.  9  shows  a  picture  of 
the  Simpson  engine  as  then  constructed  for  the  London  water 
works,  and  afterwards  in  1872  placed  in  the  water  works  of 
Philadelphia,  Pa.,  and  also  of  Lowell,  Mass.,  a  few  years  later. 
.This  type  of  pumping  engine  was  also  repeated  at  Chicago, 
Milwaukee,  Detroit,  St.  Louis,  and  other  American  cities,  and  was 
generally  credited  with  a  duty  of  from  75,000,000  to  90,000,000 
foot  pounds  per  100  pounds  of  coal  consumed  in  ordinary  good 
boiler  practice.  The  West  Side  pumping  station  of  Chicago,  at 
the  junction  of  Blue  Island  Avenue  and  Twenty-second  Street, 
has  the  largest  examples  of  the  Simpson  pumping  engines  in 
this  country ;  and  in  their  day,  in  the  early  eighties,  they  were 
no  doubt  the  most  notable  pumping  engines  this  side  of  the 
Atlantic.  Their  dimensions  are  as  follows: 

High  pressure  cylinder,  48  inches  diameter. 

Low  pressure  cylinder,  76  inches  diameter. 


30 


PUMPING  ENGINES 


High  pressure  stroke,  72  inches. 

Low  pressure  stroke,  120  inches. 

Diameter  of  pump  bucket,  51  inches. 

Diameter  of  pump  plunger,  36  inches. 

Stroke  of  bucket  and  plunger,  120  inches. 
These  engines  continued  in  service  a  good  many  years  and 
gave  very  satisfactory  general  results,  the  duty  usually  developed 
by  them  being  in  the  neighborhood  of  85,000,000  foot  pounds 


8491. 


Fig.  9.  —  Simpson's  Pumping  Engine,   1848. 

per  100  pounds  of  coal  consumed  on  the  grates  of  ordinary 
return  tubular  boilers,  according  to  well  authenticated  reports. 
About  1860  the  Worthington  duplex  pumping  engine  began 
to  appear  and  marked  an  era  in  pumping  engine  design.  Taking 
up  the  direct  acting  or  non-rotative  idea  where  the  Cornish 
engine  had  reached  its  limit  as  to  size,  economy,  and  adaptation 
to  water  works  conditions,  it  carried  on  the  march  of  improve- 
ment in  a  manner  and  to  a  degree  which  is  strongly  felt  even 
to-day,  nearly  half  a  century  later.  Instead  of  long  pit  rods 
or  heavy  weights,  the  Worthington  engine  applies  the  force  of 
steam  during  both  strokes  directly  to  the  work  to  de  done  by 


ECONOMIC  bTEAM  DUTY  31 

the  plungers,  by  means  of  direct  and  rigid  connections  between 
the  steam  pistons  and  the  water  plungers.  It  was  at  first  built 
only  of  the  horizontal  class,  and  up  to  what  would  now  be  con- 
sidered very  moderate  sizes  and  capacities,  but  later  entered  the 
vertical  field  of  design,  until  to-day  it  reaches  to  25,000,000  U.  S. 
gallons  daily  capacity  and  upwards  of  the  vertical  class.  The 
early  Worthington  engines  of  fairly  good  size  gave  an  economic 
duty  of  60,000,000  foot  pounds  per  1,000  pounds  of  steam;  and 
the  latter  day  examples  with  high  duty  attachment  develop  a 
duty  of  nearly  175,000,000  foot  pounds  under  favorable  condi- 
tions. 

Contemporary  with  the  introduction  of  the  Worthington 
duplex  pumping  engine  there  appeared  the  Holly  quadruplex 
pumping  engine,  a  crank  and  fly  wheel  engine  of  peculiar  design, 
and  this  engine  enjoyed  an  extensive  application  to  water  works 
service.  In  fact  the  Worthington  and  Holly  engines  monopolized 
and  divided  the  water  works  business  for  many  years  to  the  exclu- 
sion of  nearly  all  others,  and  were  the  forerunners  of  the  present 
commercial  pumping  engines,  the  many  repetitions  of  their 
manufacture  producing  them  at  a  price  so  far  below  that  of 
special  engines  designed  for  much  higher  steam  economy,  that 
the  slow  education  of  the  public  along  really  economic  lines,  and 
the  improvements  in  machine  shop  management,  were  necessary 
for  the  substantial  steps  forward  which  we  now  view  so  com- 
placently. The  Holly  quadruplex  pumping  engine  gave  a  duty 
of  about  85,000,000  foot  pounds  and  if  the  clearances  or  waste 
room  could  have  been  reduced  in  a  practical  manner,  the  duty 
could  no  doubt  have  been  considerably  improved. 

Early  in  the  eighties  the  competition  for  supremacy  and  busi- 
ness between  the  two  leading  types  of  water  works  pumping 
engines,  brought  about  a  sharp  line  of  demarcation  between  the 
low  duty  engines  at  low  cost  and  a  higher  duty  engine  at  a  higher 
cost,  resulting  in  the  production  of  the  Gaskill  engine  now  known 
as  the  Holly-Gaskill  or  the  Gaskill-Holly  engine;  and  then  the 
Worthington  high  duty  engine.  Both  of  these  engines  developed 
naturally  enough  along  the  previous  lines  of  practice  of  their 


32  PUMPING  ENGINES 

respective  builders,  the  Gaskill  engine  retaining  the  four 
cylinder  of  the  quadruplex,  although  differently  arranged,  the 
new  arrangement  approaching  somewhat  that  of  its  principal 
competitor,  the  Worthington,  inasmuch  as  it  embraced  four 
horizontal  steam  cylinders  and  two  horizontal  double  acting 
pumps,  the  difference  being  that  instead  of  the  tandem  arrange- 
ment the  Gaskill  took  on  the  form  of  the  Woolf  beam  type  of 
a  hundred  years  ago,  but  horizontal  instead  of  vertical.  Many 
of  the  features  of  the  valve  gear  of  its  predecessor,  the  quad- 
ruplex, were  prominent  in  the  Gaskill  design.  Its  reported 
economic  duty  of  117,936,698  ft.  Ibs.  per  1,000  Ibs.  of  steam  at 
Saratoga,  in  1884,  was  much  criticised  and  doubted  at  the  time, 
just  as  the  announcement  of  most  improvements  is  so  treated, 
but  the  value  of  small  clearances  or  waste  room  in  the  ends  of 
the  steam  cylinders  was  not  then  recognized  so  clearly  and  fully 
as  later  on.  The  writer  had  every  reason  to  believe  from  his 
own  experience  that  118,000,000  ft.  Ibs.  duty  with  compound 
pumping  engines  figured  closely  for  steam  clearance  is  a  reason- 
able record  for  moderate  sized  engines  built  on  commercial 
lines.  The  Gaskill  pumping  engine  enjoys  the  distinction  of 
being  the  first  crank  and  fly  wheel,  high  duty  pumping  engine, 
to  be  standardized  and  regularly  built  for  water  works  service. 

The  Worthington  engine  was  developed  for  high  duty  upon 
the  same  general  plan  as  formerly  constructed,  with  its  two 
high  pressure  and  its  two  low  pressure  cylinders,  two  double 
acting  water  plungers,  and  other  features  usual  in  the  earlier 
practice.  The  economic  duty  credited  to  the  Worthington 
high  duty  pumping  engine  was  just  about  the  same  as  that 
of  the  Gaskill  and  other  engines  of  the  same  multiple  expansion 
scope,  viz:  120,000,000  duty  per  1,000  Ibs.  of  steam,  or,  as  it 
was  then  the  custom  to  put  it,  per  100  Ibs.  of  coal,  upon  the 
supposition  that  the  boiler  work  would  be  10  Ibs.  of  steam  pro- 
duced per  pound  of  coal  burned  upon  the  grates. 

The  reasonableness  of  the  claims  for  a  compound  condensing 
pumping  engine,  with  cut  off  and  expansion  of  steam,  and  with 
steam  cylinders  having  a  ratio  from  high  to  low  pressure  of 


ECONOMIC  STEAM  DUTY  33 

about  four  to  one,  being  able  to  show  a  duty  of  about  120,000,000 
ft.  Ibs.  per  1,000  Ibs.  of  steam,  so  far  as  the  writer  is  concerned, 
was  based  at  the  time  upon  his  personal  experience  and  as 
time  has  passed  there  has  been  no  need  to  adversely  change 
views  upon  the  subject;  in  fact,  further  refinements  have  raised 
the  economic  duty  of  the  compound  pumping  engine  somewhat 
above  the  120,000,000  mark.  The  writer  made  a  duty  test 
with  a  Reynolds  vertical  compound  condensing  pumping  engine 
at  Hannibal,  Mo.,  November  5,  1885,  and  upon  the  basis  of 
100  Ibs.  of  coal  and  10  Ibs.  evaporation,  or  really  a  basis  of 
1,000  Ibs.  of  steam,  obtained  a  duty  of  the  then  unprecedented 
figures  under  similar  conditions  of  118,327,041  ft.  Ibs.,  and 
considering  the  fact  that  the  average  steam  pressure  was  only 
79  Ibs.  per  gauge,  it  is  fair  to  assume  that  a  somewhat  higher 
pressure  and  a  somewhat  shorter  cut-off  in  the  high  pressure 
cylinder,  would  have  raised  the  duty  a  point  or  two  above 
120,000,000  ft.  Ibs.  This  engine  was  operated  under  regular 
everyday  conditions  and  the  feed  wrater  supplied  to  the  boilers 
without  deductions  or  allowances  of  any  kind  was  taken  as 
the  steam  consumed.  The  capacity  of  the  engine  per  24  hours 
was  2,826,056  U.  S.  gallons  of  231  cubic  inches;  the  total  head 
against  the  plungers  was  249  feet,  and  the  piston  and  plunger 
speed  was  165  feet  per  minute.  The  steam  jackets  and  reheater 
consumed  10.6  per  cent  of  the  total  steam  supplied  to  the  engine 
during  the  test.  The  dimensions  of  this  engine  are  as  follows : 

One  high  pressure  cylinder,  diameter,  23  inches. 

One  low  pressure  cylinder,  diameter,  45  inches. 

Water  plungers,  each,  diameter,  17  inches. 

Stroke  of  all  pistons  and  plungers,  30  inches. 

Ratio  of  cylinders  to  each  other,  3.98  to  1. 

Volume  of  expansion  during  test,  15.03  to  1. 

Piston  and  plunger  speed,  per  minute,  165  feet. 

Average  water  pressure,  total  load,  108.12  pounds. 

Average  steam  pressure,  gauge,  79  pounds. 

Receiver  of  same  volume  as  low  pressure  cylinder. 

Two,  single  acting,  outside  packed  plungers. 


34  PUMPING  ENGINES 

The  Worthington  high  duty  engine  entered  the  field  about 
the  same  time  as  the  Gaskill  engine,  and  these  two  types  of 
pumping  machinery  for  municipal  water  supply,  represented 
two  entirely  different  schools  of  principle  in  construction, 
although  their  heat  theories  were  alike.  The  Worthington 
advocated  the  old  Cornish  principle  of  non-rotation;  while  the 
Gaskill  set  forth  as  earnestly  the  advantages  of  the  crank  and 
fly  wheel  school  of  practice;  and  these  two  engines  came  prob- 
ably as  near  to  commercial  lines  in  their  early  days  as  the 
machine  shop  tools  and  practices  of  their  time  would  permit, 
considering  also  the  more  or  less  special  features  of  adaptability 
of  any  pumping  engine  to  any  particularly  designated  plant. 


CHAPTER  IV 

THE   ADVENT   OF   TRIPLE   EXPANSION 

IN  1883  and  1884  the  Reynolds  pumping  engine  began  to 
develop  towards  a  commercial  type,  the  one  at  Hannibal,  Mo., 
referred  to  in  the  last  chapter,  being  one  of  the  earlier  specimens 
which  embodied  features  afterward  retained,  principally  among 
them  being  the  steam  valves  located  across  the  cylinder  heads, 
thus  reducing  the  clearances  or  waste  room  to  a  very  small  per- 
centage of  the  cylinder  volume;  the  outside  packed  plungers; 
and  the  vertical  type  of  machine.  One  of  the  early  develop- 
ments, after  the  Hannibal  engine,  was  the  vertical  triple  expan- 
sion for  the  high  service  station  at  Milwaukee,  Wis.,  the  first 
triple  expansion  pumping  engine  produced  in  the  world,  appear- 
ing in  1886  and  designed  to  take  the  place  of  an  engine  similar 
to  one  of  the  Hannibal  type.  In  1892  this  triple  type  of  pumping 
engine  broke  all  records  for  economic  duty  by  sending  the  figures 
up  to  154,048,700  ft.  Ibs.  per  1,000  Ibs.  of  steam,  at  the  North 
Point  pumping  station  of  the  Milwaukee  water  works. 

Higher  steam  pressures  and  higher  ratios  of  steam  expansion, 
with  the  terminal  pressure  or  the  pressure  at  the  end  of  the  expan- 
sion, remaining  at  any  certain  point,  are  the  essential  features  of 
a  higher  economic  duty.  A  clear  idea  of  the  relation  between 
expansion  and  steam  economy  may  be  grasped  by  considering 
that  the  terminal  pressure  represents  the  quantity  of  steam 
used,  while  the  mean  effective  pressure  or  the  average  pressure 
throughout  the  stroke,  represents  the  work  done  by  the  steam. 
Therefore  it  follows  that  the  greater  the  mean  effective  pressure 
in  proportion  to  the  terminal  pressure,  the  greater  will  be  the 
economy  of  steam,  and  it  also  follows  that  the  greater  the  rate 
or  ratio  of  expansion  with  any  certain  terminal  pressure,  the 

35 


36 


PUMPING  ENGINES 


higher  will  be  the  duty  of  the  engine,  provided  of  course  that 
proper  conditions  for  the  expanding  steam  are  obtained.  To 
show  this  in  a  convenient  manner  the  following  tables  have  been 
prepared  in  which  three  different  terminal  pressures  are  taken, 
and  the  mean  effective  pressures  calculated  for  12  different  steam 
pressures  per  gauge,  ranging  from  80  Ibs.  to  150  Ibs.  per  square 
inch. 

But  mere  comparison  between  the  terminal  and  mean  effective 
pressures  will  not  tell  the  whole  story,  because  the  lower  the 
terminal  pressure,  the  less  density  there  is  to  the  steam,  or 
the  less  evaporated  water  per  cubic  foot  of  the  steam.  As,  for 
example,  the  ratio  between  the  terminal  of  5  Ibs.  absolute,  and 
the  mean  effective  pressure  -for  33  expansions  is  4  to  1  with  150 
gauge  pressure.  While  at  the  other  extreme  of  the  tables,  the 
ratio  between  the  terminal  of  10  Ibs.  absolute  and  the  mean 
effective  pressure  for  9.5  expansions  is  3  to  1  with  80  Ibs.  pressure. 
But  the  steam  at  10  Ibs.  pressure  has  nearly  twice  the  density 
of  the  steam  at  5  Ibs.  pressure,  the  weights  per  cubic  foot 
being: 

.02641  of  a  pound  at  10  pounds  pressure,  per  cubic  foot. 

.01373  of  a  pound  at  5  pounds  pressure,  per  cubic  foot. 

With  a  low  pressure  cylinder  having  say  3,000  square  inches 
of  piston  area,  or  a  little  over  60  inches  diameter,  at  200  feet  per 
minute  travel  of  piston,  with  all  steam  accounted  for  by  the 
indicator  diagram,  with  no  steam  used  in  the  jackets  or  reheater, 
and  with  2.48  Ibs.  deducted  for  the  best  practical  vacuum,  the 
duty  would  be  as  follows : 


GAUGE 
PRESSURE. 

ABSOLUTE 
TERMINAL. 

MEAN 
EFFEOVIVE 
PRESSURE. 

RATIO  OF 
EXPANSION. 

DUTY  PER  1,000  LBS. 
OF  STEAM. 

80 
150 

10 
5 

30.03 
20.00 

9.5 
33.0 

162,324,324 

206,898,103 

This  shows  a  gab  in  economic  duty  of  27  per  cent  without 
allowing  any  steam  to  be  used  in  the  jackets;  with  an  engine  as- 


THE  ADVENT  OF  TRIPLE  EXPANSION 


37 


actually  operated,  and  with  steam  used  in  the  jackets  and  re- 
heaters,  the  difference  in  actual  economy  was  much  more  than 
this,  between  the  first  triple  expansion  pumping  engine,  and  the 
engine  holding  the  record  at  the  end  of  the  year  1900,  but  of 
course  some  allowance  must  be  made  for  the  practical  improve- 
ments in  pumping  engines  between  1886  and  1900,  although 
from  1900  to  1906  the  gain  in  duty  was  only  0.89  of  one  per 
cent.  The  difference  in  duty  between  1886  and  1900  was  as 
follows : 

First  triple  in  1886,  round  numbers,  129,000,000  duty. 

The  record  in  1900,  round  numbers,  179,000,000  duty. 

This  shows  a  gain  of  38  per  cent  in  actual  practice  and  with  the 
gauge  steam  pressure  raised  only  from  80  Ibs.  to  126  Ibs.  But 
the  later  engine  had  poppet  valves  on  the  low  pressure  cylinder, 
thereby  reducing  the  clearance  to  probably  one  half  per  cent  or 
lower. 

The  high  duty  record  from  1893  to  April,  1906,  all  held  at  the 
various  periods  by  the  vertical  triple  expansion,  crank,  and  fly 
wheel  pumping  engine  using  steam  jackets  and  reheaters,  is  as 
follows: 


YEAH. 

FT.  LBS.  PER  1,000  LBS. 
OF  STEAM. 

1893    .... 

154,048,700 

1895  _  .  .  . 
1898 

157,843,000 
167  800  000 

1900 

168  532  800 

1900  .  .  . 

178  497  000 

1900  

179,419,600 

1906  

181,068,605 

Following  in  tabulated  form  may  be  seen  the  ratios  of  expan- 
sion possible  with  different  gauge  pressures,  and  with  different 
terminal  pressures.  The  terminal  and  mean  effective  pressures 
being  absolute  or  above  perfect  vacuum,  and  the  expansion 
under  the  various  pressures  assumed  to  be  as  good  as  would  be 
indicated  by  the  Mariotte  curve. 


38 


PUMPING  ENGINES 


First :   With  a  terminal  of  5  pounds  absolute. 


GAUGE  PRESSURE. 

MEAN  EFFECTIVE 
PRESSURE. 

EXPANSIONS. 

80 

19.72 

19 

90 

20.02 

21 

100 

20.67 

23 

110 

21.18 

25 

115 

21.29 

26 

120 

21.47 

27 

125 

21.66 

28 

130 

21.84 

29 

135 

22.00 

30 

140 

22.16 

31 

145 

22.32 

32 

150 

22.48 

33 

Second :   With  a  terminal  of  7  pounds  absolute. 


GAUGE  PRESSURE. 

MEAN  EFFECTIVE 
PRESSURE. 

EXPANSIONS. 

80 

23.37 

13.5 

90 

25.96 

15 

100 

26.64 

16.4 

110 

27.15 

17.8 

115 

27.49 

18.5 

120 

27.67 

19.3 

125 

27.98 

20 

130 

28.13 

20.7 

135 

28.35 

21.4 

'      140 

28.67 

22.1 

145 

28.80 

22.8 

150 

29.18 

23.5 

Third :    With  a  terminal  of  10  pounds  absolute. 


GAUGE  PRESSURE. 

MEAN  EFFECTIVE 
PRESSURE. 

EXPANSIONS. 

80 

32.50 

9.5 

90 

33.50 

10.5 

100 

34.41 

11.5 

110 

35.26 

12.5 

115 

35.65 

13 

120 

36.02 

13.5 

125 

36.39 

14 

130 

36.74 

14.5 

135 

37.08 

15 

140 

37.40 

15.5 

145 

37.72 

16 

150 

38.00 

16.5 

THE  ADVENT  OF  TRIPLE  EXPANSION  39 

These  mean  effective  or  average  working  pressures  throughout 
the  stroke  of  the  piston  are  absolute  pressures  or  pressures  above 
an  absolute  and  perfect  vacuum ;  and  the  proportion  of  percent- 
age of  these  pressures  possible  to  actually  obtain  for  useful  work 
within  a  steam  cylinder,  will  depend  of  course  upon  the  value  or 
perfection  of  the  vacuum  maintained  within  the  low  pressure 
cylinder  of  a  triple  expansion  engine;  it  being  considered  quite 
out  of  the  question  to  use  one  cylinder  with  a  condenser,  in  eco- 
nomically carrying  such  high  ratios  of  expansion,  even  with  the 
lowest  initial  pressure  given  in  the  gauge  pressure  column  of 
these  tables. 

During  the  past  25  years  there  has  probably  been  nothing 
concerning  the  capabilities  of  pumping  machinery  so  much  dis- 
cussed as  its  economic  duty;  or,  the  ability  or  inability  to  develop 
more  or  less  foot  pounds  of  work  upon  one  basis  or  another  of 
comparison,  but  mostly  per  1,000  Ibs.  of  steam  consumed,  or  per 
1,000,000  heat  units  utilized.  Twenty-five  years  ago  60,000,000 
foot  pounds  duty  was  the  general  guarantee  for  water  works 
engines,  with  occasionally  an  engine  of  special  design  aiming  to 
show  100,000,000  foot  pounds,  the  advocates  of  the  higher  type 
and  more  costly  machine  arguing  that  the  saving  in  fuel  repre- 
sented by  the  greater  economy  would  more  than  pay  the  interest 
upon  the  difference  in  the  cost  of  the  machinery.  This  saving 
was  a  fact,  upon  the  showing  of  the  test  and  trial  runs,  provided 
the  engines  were  equal  in  other  respects,  principally  as  to  the 
ability  to  successfully  and  continually  pump  water  without 
unusual  interruption  on  account  of  stoppage,  breakdown,  and 
needed  repairs. 

Years  ago  the  writer  took  the  ground  that  the  first  duty  of  a 
pumping  engine  was  to  pump  water,  and  sees  no  reason  to  change 
that  idea  to-day;  but  in  the  early  days  as  a  general  rule  the 
pumping  engines  of  a  higher  duty  than  about  60,000,000  foot 
pounds,  were  not  built  quite  so  sturdy  for  the  hard  work  of 
pumping,  as  their  lower  duty  competitors,  and  if  durability, 
smoothness  of  operation,  and^  decreased  cost  had  not  gradually 
forged  to  the  front,  in  the  construction  of  pumping  machinery, 


40  PUMPING.  ENGINES 

for  water  works,  the  present  admirable  results  would  not  have 
been  attained. 

The  expansion  of  the  steam  is  the  key  of  course  to  higher  and 
higher  economy,  but  as  this  factor  was  increased  in  ratio  from 
time  to  time  and  gradually  approached  its  physical  limits,  new 
difficulties  arose  one  after  another,  or  were  more  and  more 
realized  as  greater  attempts  at  higher  economy  were  made;  but 
after  persistent  efforts  along  encouraging  lines  the  happy  com- 
promise seems  to  at  last  have  been  reached  between  a  highly 
elastic  gas  at  one  end  of  a  machine,  and  a  non-elastic  most 
stubborn  fluid  at  the  other  end,  and  with  the  limit  of  steam 
economy  very  nearly  reached.  In  the  early  days  of  steam 
expansion  to  high  ratios,  it  did  not  at  first  seem  to  be  realized 
that  the  impact  upon  a  steam  piston  of  a  very  high  initial  pres- 
sure as  against  the  corresponding  effect  of  a  low  pressure,  would 
greatly  increase  the  shocks  and  possible  damage  to  the  machine. 
Under  certain  conditions,  as  in  mill  engines,  the  initial  shock  of 
the  steam  may  be  absorbed  by  adjusting  the  weight  and  motion 
of  the  moving  parts  to  meet  the  sudden  impulse  of  the  incoming 
steam  as  the  steam  or  induction  valve  is  quickly  opened;  the 
piston  traveling  toward  the  end  of  its  stroke  must  of  course 
stop  before  it  can  make  a  return  stroke,  and  although  the 
unaided  eye  cannot  determine  the  instant  of  the  stoppage,  it 
nevertheless  actually  takes  place  for  the  simple  reason  that  it 
is  physically  impossible  for  it  to  go  in  both  directions  at  the 
same  time. 

But  having  once  stopped,  or  come  to  rest  even  if  only  for  the 
shortest  imaginable  fraction  of  a  second,  it  must  be  started  again, 
and  if  the  weight  of  the  moving  parts  such  as  the  piston  rod, 
piston,  crosshead,  and  connecting  rod,  can  be  made  to  just  about 
equal  the  effort  of  the  initial  steam  then  the  shock  is  taken  up  by 
the  inertia  of  the  mass.  The  speed  of  the  crank  pin  in  its  circle 
or  orbit  of  revolution,  is  practically  the  same  at  all  points,  but 
the  driving  parts  of  the  engine  moving  only  along  the  line  across 
the  circle,  must  of  course  start  from  no  motion  at  the  beginning 
of  the  stroke,  come  up  to  full  speed  of  the  crank  pin  at  the  middle 


. 

THE  ADVENT  OF  TRIPLE  EXPANSION  41 

of  the  stroke,  and  then  subside  to  no  motion  again  at  the  end  of 
the  stroke.  This  means  that  the  speed  of  the  moving  parts  must 
be  accelerated  or  increased  and  retarded  or  diminished  twice  at 
each  revolution  of  the  crank  shaft.  And  the  effect  of  this  is 
precisely  the  same  as  that  of  centrifugal  force  at  the  beginning 
and  end  of  the  stroke,  the  calculation  for  the  force  required  to 
start  the  weight  at  the  beginning  of  the  stroke  being  the  same 
as  that  for  determining  centrifugal  force  which  the  weight 
exerts  in  trying  to  pull  away  from  the  center  when  rapidly 
revolved.  If  a  plumb  bob  be  attached  to  a  piece  of  cord,  say  6 
feet  long,  and  swung  around  in  a  horizontal  circle  just  above 
one's  head,  the  pull  or  pressure  exerted  by  the  centrifugal  force, 
or  the  force  due  to  the  revolution  of  a  weight,  can  be  easily  felt 
by  the  hand,  and  this  pull  or  force  is  precisely  what  the  steam 
will  meet  at  the  beginning  of  the  stroke,  so  that  if  the  force  can 
be  nearly  or  practically  balanced  against  the  incoming  steam 
pressure,  then  smoothness  and  absence  of  wearing  shock  will 
be  the  result.  In  the  latter  half  of  the  stroke  the  work  repre- 
sented by  the  rapidly  moving  weight  brought  up  to  the  full 
speed  of  the  revolving  crank  pin  at  each  stroke,  is  utilized  in 
helping  to  push  the  crank  pin  along  its  way  until  the  end  is  again 
reached  and  the  incoming  steam  again  takes  up  the  work  for 
another  stroke.  Thus  the  first  half  of  the  stroke  stores  up  the 
energy  of  the  moving  parts,  which  is  again  given  out  by  these 
parts  during  the  last  half  of  the  stroke. 

This  initial  force  is  easily  calculated  from  the  fact  that  many 
experiments  for  the  determination  of  how  much  centrifugal 
force  amounts  to,  has  demonstrated  that  one  pound  weight  at 
the  end  of  a  crank  one  foot  long,  and  making  one  revolution  per 
minute,  will  exert  a  force  pulling  away  from  the  center,  of 
0.000341  of  a  pound,  or  thirty-four  thousandths  of  one  per  cent 
of  a  pound  nearly.  The  relation  of  this  amount  of  force  to 
other  conditions  involving  other  weights,  other  lengths  of  crank, 
and  other  rates  of  revolution  has  resulted  in  the  establishing 
of  a  formula  or  rule  of  calculation  to  the  effect  that  the  cen- 
trifugal force  will  vary  in  accordance  with  the  following: 


42  PUMPING  ENGINES 

It  will  vary  directly  according  to  the  weight  in  pounds. 
Directly  according  to  the  length  of  the  crank  in  feet. 
According  to  the  square  of  the  revolutions  per  minute. 
NOTE.  —  The  square  of  the  revolutions  per  minute,  means  the  number 
of  revolutions  per  minute,  multiplied  by  itself. 

The  expression  of  the  formula  is : 
Centrifugal  force  =  W  X  R2  X  L  X  .000341. 

W  represents  the  weight  in  pounds. 

R2  represents  revolutions  per  minute  multiplied  by  itself. 

L  represents  the  length  of  the  crank  in  feet. 

.000341  represents  the  centrifugal  force  of  one  pound  making 

one  revolution  per  minute  at  the  end  of  a  crank  one 

foot  long. 

To  show  how  this  force  will  apply  in  practice  take,  for  exam- 
ple, a  30-inch  steam  cylinder  working  condensing,  indicating  40 
Ibs.  mean  effective  pressure  throughout  the  stroke;  in  one  case 
using  100  Ibs.  steam  pressure  with  8  expansions,  the  initial  load 
upon  the  piston  would  be  78;512  Ibs.,  while  in  another  case  using 
70  Ibs.  steam  pressure  in  a  throttling  engine  getting  the  same 
mean  effective,  the  initial  load  upon  the  piston  would  be  about 
43,000  Ibs. 

With  100  Ibs.  initial  pressure  and  10  expansions  the  mean 
effective  pressure  would  be  33  Ibs.  net,  with  an  initial  load  of 
78,512  Ibs.  as  before,  but  the  initial  piston  load  upon  the 
throttling  engine  would  be  35,300  Ibs. 

With  125  Ibs.  initial  pressure  and  15  expansions  the  mean 
effective  pressure  would  be  30  Ibs.  net,  with  an  initial  load  of 
93,722  Ibs.,  while  the  initial  load  upon  the  piston  of  a  corre- 
sponding throttling  engine  would  be  only  31,770  Ibs. 

This  enormous  difference  in  impact  of  initial  pressures,  coupled 
with  the  great  amount  of  internal  condensation  within  the  steam 
cylinder  when  too  high  a  rate  of  expansion  was  attempted  in  one 
cylinder,  had  a  powerful  effect  in  bringing  about  the  very  great 
extent  to  which  load  distribution  is  now  made  throughout  the 
machine  as  a  purely  mechanical  problem;  also  the  thermal 


f 

THE  ADVENT  OF   TRIPLE  EXPANSION  43 

idea  of  dividing  the  expansion  into  different  stages  and  so 
reduce  the  range  of  temperature  in  each  of  the  cylinders  em- 
ployed, more  fully  referred  to  in  Chapter  V,  which  deals  with 
the  Mariotte  curve  of  expansion. 

The  adaptation  of  the  pumping  engine  to  its  conditions  and 
surroundings  so  far  as  may  be,  is  the  real  key  to  highest  efficiency 
under  the  particular  conditions  imposed.  There  are  advocates 
of  high  speed,  of  high  steam  pressure,  of  high  rate  of  revolution, 
and  other  singled  out  and  isolated  factors,  but  the  general  com- 
bination wherein  the  machine  best  meets  the  conditions  is  what 
will  yield  the  best  results,  and  not  the  exploiting  of  any  particular 
seemingly  important  factor  by  itself.  And,  as  an  example  of 
this  fact,  it  may  be  noted  that  the  pumping  engine  in  this  coun- 
try, if  not  in  the  world,  which  up  to  April  of  1906  held  the  high 
duty  record  has  the  following  conditions  to  work  under : 

Capacity  per  24  hours,  15,000,000  U.  S.  gallons. 

Piston  speed,  197  feet  per  minute. 

Rotative  speed,  16.41  revolutions  per  minute. 

Water  load  against  plungers,  126  pounds  pressure. 

Steam  pressure  per  gauge,  126  pounds  pressure. 

Energy  of  steam  end,  802  indicated  horse  power. 

Energy  of  water  end,  770  horse  power. 

Mechanical  efficiency  of  the  machine,  96  per  cent. 

Steam  per  hour  per  indicated  horse  power,  10.68  pounds. 

Duty  per  1,000  pounds  of  steam,  179,454,250  ft.  Ibs. 
Since  the  above  record  was  made  in  1900  it  has  remained  at 
the  top  of  the  list  until  April  of  1906,  when  a  similar  engine  newly 
installed  in  the  same  plant  raised  it  to  181,068,605,  or  a  gain  of 
0.89  of  one  per  cent,  which  again  emphasizes  the  idea  that  the 
limit  is  very  nearly  if  not  quite  reached.  This  last  record  is  so 
slightly  in  excess  of  its  immediate  predecessor  that  it  requires 
several  repetitions  before  it  can  be  accepted  as  final,  the  error, 
cleverness,  and  good  fortune  attending  some  of  these  per- 
formances requiring  at  least  one  per  cent  leeway. 

Regarding  high  piston  speed,  the  best  record  known  to  the 
writer  as  to  pumping  engines  is  607  feet  per  minute,  where  the 


44 


PUMPING  ENGINES 


duty  per  1,000  Ibs.  of  steam  was  157,843,000  ft.  Ibs.,  showing 
that  higher  piston  speed  alone  will  not  answer  the  purpose. 

Regarding  high  steam  pressure,  the  record  seems  to  be  200  Ibs. 
and  a  duty  of  149,500,000  ft,  Ibs.,  showing  that  high  steam  pres- 
sure in  the  absence  of  other  ruling  conditions  or  proper  fitness 
falls  short  of  the  best  performance. 

Regarding  thermal  efficiency ,  or  the  actual  economy  of  the 
heat  employed,  with  reference  to  absolute  temperatures,  even 
the  greatest  thermal  efficiency  does  not  in  the  presence  of  adverse 
conditions  in  some  other  direction,  equal  the  engine  working 
under  the  best  general  fitness  of  things  as  will  be  seen  by  the 
following  taken  from  the  records : 


THERMAL  EFFICIENCY. 

DUTY  PEK  1,000  POUNDS  OF 
STEAM. 

Per  Cent. 

Foot  Pounds. 

22.80 
21.63 
21.00 
20.85 

20.78 

149,500,000 
178,497,000 
179,454,250 
173,620,000 
176,419,600 

What  was  considered  the  record  up  to  April,  1906,  for  general 
all  around  efficiency  for  a  pumping  engine,  and  may  yet  be  even 
after  the  particulars  of  the  new  record  maker  of  181,061,605  ft. 
Ibs.  per  1,000  Ibs.  of  steam  become  known,  is  as  follows: 

Capacity  per  24  hours,  30,000,000  U.  S.  gallons. 

Steam  pressure  per  gauge,  185  pounds. 

Piston  speed,  195  feet  per  minute. 

Duty  per  1,000  Ibs.  of  steam,  178,497,000  ft.  Ibs. 

Duty  per  million  heat  units,  163,925,300  ft.  Ibs. 

Steam  per  indicated  horse  power  hour,  10.335  pounds. 

Thermal  efficiency,  21.63  per  cent. 

The  highest  record  for  thermal  efficiency  is  22.80  per  cent, 
which  is  5.4  per  cent  above  this  all  around  record  holder;  but  the 
latter  shows  a  duty  per  1,000  Ibs.  of  steam  which  is  19.39  per  cent 
above  the  former. 


THE  ADVENT  OF  TRIPLE  EXPANSION  45 

Up  to  April,  1906,  the  highest  record  for  duty  per  1,000  Ibs. 
of  steam  was  179,454,250  ft.  Ibs.  which  is  only  0.54  of  one  per 
cent  above  the  all  around  machine,  but  the  latter  shows  a 
thermal  efficiency  of  3.1  per  cent  above  the  former. 

With  reference  to  the  steam  economy  of  these  higher  types  of 
pumping  engines  and  its  repetition  in  different  engines,  it  may  be 
noted  that  covering  a  period  of  more  than  5  years,  five  pumping 
engines  of  a  similar  type,  by  different  builders,  and  situated  many 
miles  apart,  gave  steam  per  indicated  horse  power  ranging 
through  the  following  figures: 


10.33  pounds  per  horse  power  hour. 
10.63  pounds  per  horse  power  hour. 
10.78  pounds  per  horse  power  hour. 
11.01  pounds  per  horse  power  hour. 
11.10  pounds  per  horse  power  hour. 


As  already  pointed  out,  it  hardly  seems  probable  that  materi- 
ally higher  efficiencies  will  be  obtained  in  the  near  future,  and 
not  very  much  higher  duties  are  possible  with  the  steam  pres- 
sures seemingly  practicable  to  employ  in  pumping  stations,  in 
fact,  so  far  at  least,  the  use  of  quadruple  expansions  and  200  Ibs. 
steam  pressure  has  not  resulted  in  so  good  work  as  the  triple 
expansion  with  126  Ibs.  pressure.  Indeed  the  employment  of 
250  Ibs.  steam  pressure  and  50  expansions  does  not  promise 
even  theoretically  very  much  gain;  and  practically,  in  large 
pumping  units  available  practice  is  against  such  an  advance  in 
the  difficult  line  of  high  expansion.  Superheat  will  no  doubt 
carry  the  results  to  slightly  higher  figures  than  at  present,  but 
the  conditions  must  be  very  carefully  met  to  make  it  profitable 
to  the  owner  and  user.  Net  gain  is  what  is  sought,  and  fancy 
duty  figures  at  the  expense  of  heat  and  repairs  in  some  other 
part  of  the  plant  will  not  add  to  the  real  economy  in  the  long 
run.  But  however  the  steam  or  heat  efficiency  may  be  im- 
proved, or  however  many  times  the  present  record  may  be 
reached  in  the  future,  the  durability  of  the  machinery  for  the 
purpose  of  its  existence  comes  first  and  should  not  be  sacrificed 


46 


PUMPING  ENGINES 


to  any  fancied  betterment  in  steam  economy  only.  The  fol- 
lowing table  shows  the  economical  efficiency  of  the  higher  types 
of  pumping  engines  produced  from  1893  to  1903  and  includes 
about  all  of  the  prominent  builders  in  this  country. 


DATE  OF 
RECORD 

OF 

ENGINE 
TEST. 

CAPACITY 
IN  GALLONS 

PER 

24  HOURS. 

PISTON 
SPEED 
FEET 

PER 

MINUTE, 

TOTAL 
WATER 
LOAD 
POUNDS 
PRESSURE. 

GAUGE 
STEAM 
PRES- 
SURE IN 
POUNDS. 

THERMAL 
EFFICIENCY 

IN  PER 

CENT. 

DUTY  PER 
1,000  POUNDS 
STEAM. 

1893 

18,000,000 

203 

71 

121 

19.40 

154,048,700 

1894 

16,000,000 

371 

84 

137 

19.07 

148,655,000 

1895 

20,000,000 

607 

60 

176 

20.76 

157,843,000 

1897 

30,000,000 

208 

86 

167 

18.35 

152,000,000 

1898 

20,000,000 

215 

89 

156 

20.45 

167,800,000 

1899 

20,000,000 

200 

88 

149 

19.90 

165,220,000 

1899 

6,000,000 

256 

262 

200 

22.80 

149,500,000 

1899 

10,000,000 

175 

128 

136 

18.44 

160,455,000 

1899 

10,000,000 

175 

128 

137 

18.59 

161,530,000 

1900 

12,000,000 

211 

115 

173 

20.00 

168,532,000 

1900 

15,000,000 

198 

127 

127 

20.78 

176,419,600 

1900 

15,000,000 

197 

126 

126 

21.00 

179,454,250 

1900 

30,000,000 

195 

61 

185 

21.63 

178,497,000 

1901 

21,000,000 

496 

82 

178 

19.43 

146,173,000 

1901 

35  000,000 

300 

20 

151 

20.50 

157,349,000 

1901 

20,000,000 

248 

54 

150 

20.85 

173,620,000 

1903 

10,000,000 

480 

80 

181 

18.95 

140,000,000 

1903 

15,000,000 

197 

127 

138 

20.72 

177,300,000 

1903 

15,000,000 

197 

127 

135 

20.67 

177,200,000 

In  the  above  table  the  first  engine  is  a  vertical  triple;  the 
second  one  a  vertical  compound;  the  third,  fourth,  fifth,  and 
sixth  are  vertical  triples;  the  seventh  is  a  quadruple;  and  the 
rest,  with  the  exception  of  the  seventeenth  which  is  a  vertical 
compound,  are  vertical  triples. 


CHAPTER  V 

THE   MARIOTTE   CURVE 

THE  Mariotte  law  of  expanding  gases  was  discovered  by  Edme 
Mariotte,  Prior  of  St.  Martin,  and  one  of  the  first  members  of 
the  Academy  of  Sciences  which  was  founded  at  Paris,  France, 
in  1666.  He  was  a  native  of  Burgundy,  and  died  in  1684  after  a 
long  and  useful  life. 

This  law  was  also  discovered  by  Boyle  in  1662,  separately  from 
and  independently  of  Mariotte,  and  is  sometimes  called  Boyle's 
law,  especially  in  England,  but  on  the  Continent  of  Europe 
and  in  this  country  is  mostly  known  as  Mariotte 's  law  of  volume 
and  pressure  of  gases.  It  is  laid  down  in  the  reference  books  as 
follows : 

The  temperature  remaining  the  same,  the  volume  of  a  given 
quantity  of  gas  is  inversely  as  the  pressure  which  it  bears. 

That  is  to  say,  when  the  temperature  of  a  gas  does  not  change 
from  a  higher  to  a  lower  degree,  or  the  reverse,  if  the  volume  or 
cubic  contents  is  reduced  to  one  half  of  what  it  was  formerly, 
its  pressure  will  be  doubled.  Or,  if  the  gas  under  the  same  con- 
ditions of  temperature  is  increased  in  volume  so  as  to  fill  twice 
the  space  as  before,  its  pressure  will  be  reduced  to  one  half. 
And  this  effect  will  follow  any  other  proportionate  change  in 
volume;  four  times  the  volume  makes  one  fourth  the  pressure; 
one  fourth  the  volume  makes  four  times  the  pressure ;  and  so  on 
to  five,  to  six  or  any  other  relative  change  apparently  up  to 
twenty-seven  at  least  and  that  is  as  far  as  experiments  were 
carried  of  a  similar  nature. 

This  law  has  been  considered  and  experimented  with  by  dif- 
ferent investigators  and  found  to  be  correct  up  to  at  least  400 
Ibs.  pressure  per  square  inch,  so  we  may  consider  it  conclusive 

47 


48  PUMPING  ENGINES 

so  far  as  it  fits  the  case,  and  so  far  as  ordinary  useful  pressures 
for  pumping  engines  are  concerned.  The  law  can  be  very  easily 
demonstrated  by  a  glass  tube  bent  like  a  letter  U  with  the  open 
ends  of  the  tube  uppermost  and  with  the  straight  parts  of  the  U 
vertical.  One  leg  of  the  U  is  much  shorter  than  the  other,  and 
near  the  lower  end  of  the  U  close  to  the  bend  there  is  marked 
a  level  line  and  up  to  this  line,  in  both  legs,  a  small  quantity  of 
mercury  is  poured,  making  the  surface  of  the  mercury  in  both 
legs  alike  in  level.  By  stopping  up  the  top  of  the  short  leg  and 
pouring  additional  mercury  into  the  long  leg,  the  result  will  be 
that  when  the  body  of  imprisoned  air  has  been  reduced  to  half 
its  original  volume  at  the  closed  end  of  the  glass,  the  height  of 
the  mercury  will  show  that  the  pressure  is  doubled.  The  reverse 
can  be  shown  by  reversing  the  tube  so  that  it  will  be  inverted 
from  its  original  position,  and  then  the  mercury  will  indicate  half 
the  pressure  when  the  volume  of  the  original  air  has  been  doubled. 

The  law  provides  that  the  temperature  remain  the  same,  and 
this  provision  can  be  satisfied  in  the  glass  tube  experiment ;  but 
with  cylinders  and  pistons  doing  work  by  the  expansion  of  a  gas 
or  fluid,  the  temperature  of  the  air  or  any  other  gas  would  not 
remain  the  same,  but  would  cool  by  expansion  and  heat  by 
compression. 

The  writer  had  occasion  several  years  ago  to  examine  and 
report  upon  a  large  air  compressing  and  operating  plant  at  Iron 
Mountain,  Mich.  The  object  of  this  plant  was  to  compress  air 
by  means  of  water  power  at  Menominee  Falls,  and  send  the 
compressed  air  under  60  Ibs.  pressure  four  miles  through  a  24- 
inch  steel  main  to  the  Chapin  and  Ludington  iron  ore  mines  for 
operating,  pumping,  drilling,  hoisting,  and  other  kinds  of  mining 
machinery.  The  air  compressor  cylinders  were  32  inches  diame- 
ter and  of  60  inches  stroke  of  pistons ;  in  compressing  the  free  air 
up  to  60  Ibs.  pressure  an  indicator  diagram  showed  that  about 
20  per  cent  was  added  to  the  area  of  the  diagram  by  the  heating 
of  the  air  up  to  from  250  to  300  degrees  Fahrenheit.  This  heat 
was  represented  by  772  foot  pounds  for  each  amount  of  the 
heat  that  would  raise  one  pound  of  water  one  degree,  from  39 


THE  MARIOTTE  CURVE  49 

degrees  Fahrenheit.  At  the  mine,  four  miles  from  the  falls,  the 
air  had  cooled  down  to  atmospheric  temperature,  where  a  large 
bob  pump  was  worked  by  a  Reynolds-Corliss  engine,  24  by 
48,  at  50  revolutions  per  minute,  and  the  indicator  cards  showed 
a  shrinkage  in  the  diagrams  of  about  15  per  cent  at  the 
expansion  curve,  expanding  from  60  initial  down  to  the  ordinary 
atmospheric  pressure.  In  the  absence  of  a  small  steam  jet 
which  was  kept  going  in  the  exhaust  chamber  of  the  engine 
cylinder,  and  which  was  shut  off  now  and  then  for  experi- 
menting, frost  would  form  on  the  back  cylinder  head  with  the 
sun  shining  full  upon  it ;  the  air  remaining  perfect  air,  of  course, 
during  these  operations  of  absorbing  and  giving  out  heat, 
because  air  is  a  perfect  gas  and  the  heat  has  no  part  in  its 
composition. 

However,  steam  is  not  a  perfect  gas,  like  air,  oxygen,  hydrogen, 
and  other  gases.  Steam  is  a  mixture  of  heat  and  water,  and 
those  two  elements  quickly  separate  when  left  to  themselves 
without  additional  heat  to  make  up  for  the  inevitable  losses 
from  radiation  or  work.  "  Consequently,  in  an  actual  engine 
cylinder,  and  doing  work,  marked  disturbances  take  place;  and 
this  imitation  gas  which  we  call  steam  suffers  at  the  beginning 
of  the  stroke  and  recuperates,  and  a  little  more,  at  the  latter  por- 
tion of  the  stroke ;  the  general  result  on  an  indicator  card  in  very 
good  practice  being  a  pretty  close  copy  of  the  Mariotte  expan- 
sion curve  by  a  perfect  gas;  and,  if  we  treat  the  expansion, 
quantity  of  steam,  and  the  work  done,  by  steam  in  an  engine, 
strictly  according  to  the  form  of  the  Mariotte  curve,  it  will  be 
seen  that  the  results  arrived  at  are  very  desirable  and  hard  to 
attain  in  the  actual  practice  with  steam  engines. 

It  is  a  case  of  a  balancing  of  errors,  and  gives  the  advantage 
of  showing  what  may  be  done  by  what  might  be  called  a  reflected 
light.  But  the  reflected  light  shows  the  road  just  the  same. 
The  variation  in  conditions  of  actual  steam,  heat,  and  work, 
are  so  many,  the  fluctuations  of  values  in  the  materials  used  are 
so  great  and  so  incessant,  that  it  is  absolutely  impossible  to  lay 
CUt  in  advance  a  scientific  sharp  line  which  can  be  hewn  to.  And 


50  PUMPING  ENGINES 

therefore  to  the  writer  it  seems  to  be  much  better  to  have  a  hard 
and  fast  line  to  go  by,  amendable  to  mathematical  precision, 
and  capable  of  being  produced  on  every  and  on  all  occasions  for 
purposes  of  seeing  just  where  we  are  at  any  time.  In  short, 
if  the  engineer  sets  up  the  Mariotte  curve  and  law,  and  assumes 
perfectly  dry  steam,  he  will  have  a  much  better  light  to  look 
forward  by,  than  he  will  by  endeavoring  to  account  for  all  the 
variations  which  he  will  surely  meet  in  trying  to  follow  all  of  the 
actual  facts ;  and  he  will  find  that  considering  the  actual  consump- 
tion of  steam  and  fuel,  he  will  get  better  results  in  pumping 
water.  Not  only  that,  he  will  find  in  working  out  his  salvation 
by  the  Mariotte  curve,  that  he  will  approximate  very  closely 
indeed  to  proportions  and  dimensions  which  produce  the  highest 
results  in  actual  steam  practice,  as  will  be  shown  further  along 
in  this  book.  There  are  other  curves  in  the  expansion  diagram, 
carrying  the  line  a  trifle  below  and  inside  of  the  Mariotte  curve, 
requiring  a  deeper  look  into  the  science  of  thermodynamics 
than  the  writer  deems  desirable  in  a  book  of  this  scope.  But 
such  curves,  although  necessary  to  follow  and  plot  out  in  obtain- 
ing a  good  theoretical  grasp  of  the  subject,  can  never  be  normally 
made  by  an  indicator  attached  to  a  steam  engine;  and,  as  the 
Mariotte  line  is  the  very  best  that  can  be  made  in  practice  with- 
out leakage  or  condensation,  it  is  the  one  thought  best  to  be 
used  for  the  purposes  of  illustration. 

Considering  the  foregoing  then,  the  following  examples  are 
based  upon  the  Mariotte  expansion  curve,  perfectly  dry  steam, 
all  working  steam  accounted  for  by  the  indicator  diagrams,  and 
allowing  for  no  clearance  or  waste  room  hi  the  steam  cylinders. 
Indeed  the  waste  room  has  been  brought  down  to  such  a  fine 
point,  less  than  half  of  one  per  cent,  hi  many  cylinders,  that  it 
can  practically  be  neglected  as  there  are  other  disturbances  of 
more  consequence.  The  diagrams  in  these  examples  are  made  to 
conform  to  the  Mariotte  curve  as  the  standard  for  comparison 
for  all  steam  expansion  curves.  This  curve  is  a  mathematical 
one  and  easily  determined;  being  a  hyperbola  readily  laid  out 
according  to  its  law  of  relative  volumes  and  pressures,  and  its 


THE  MARIOTTE  CURVE  51 

effects  may  be  readily  calculated  by  means  of  the  simple  rule 
and  a  table  of  hyperbolic  logarithms.  The  Mario tte  is  about  the 
best  curve  that  can  be  accomplished  in  actual  practice  and  in 
fact  it  is  rather  difficult  in  the  absence  of  leakage  or  other 
undesirable  conditions  to  get  the  expansion  down  even  to  this 
curve.  The  other  curves  mentioned  above,  determined  by  intri- 
cate theoretical  and  mathematical  considerations,  show  the 
expansions  of  steam  after  all  is  accounted  for  as  going  a  little 
lower  than  that  of  the  Mariotte  law,  and  therefore  indicating 


165  Ibs.  absolute  pressure. 
150  Ibs.  Gauge  pressure. 
Initial  steam  pressure. 
Temperature 


Range  of  Temperature  from  Initial  Pressure  to  Terminal  Pressure 
365-162.203*  Pahr. 


84"  Cylinder  x  66" Stroke 

M.E.P.  =  22.48  Ibs.  absolute. 

755  Horse  Power  at  200  feet  piston  speed. 

Cut-off  =  2"  from  beginning  of  stroke 

Ratio  of  expansion  =  33  to  1. 


5  Ibs.  absolute  terminal  pressure. 

1 

162°  Temperature,  Falir. 

Fig.  10.  —  The  Mariotte  Curve  in  a  Single  Cylinder. 

a  trifle  better  economy  of  steam,  if  such  curves  could  be  honestly 
made  by  an  indicator  attached  to  a  steam  cylinder.  But  as 
there  is  very  little  difference  after  all,  and  as  the  very  best  curves 
made  in  practice  essentially  coincide  with  that  of  the  Mariotte 
law,  the  diagrams  used  for  these  illustrations  may  be  taken  as 
practically  correct;  about  the  only  remaining  question  being  as 
to  how  far  will  the  indicator  account  for  the  steam  used,  which 
after  all  leads  to  a  further  question  as  to  the  quality  of  the 
steam  at  the  low  pressure  terminal,  it  being  a  pretty  fair 
assumption  that  with  the  low  pressure  terminal  perfectly  dry, 
and  not  materially  superheated,  about  all  of  the  working  steam 


52  PUMPING  ENGINES 

will  be  accounted  for  by  the  pressure  shown  and  the  volume 
expressed  by  the  low  pressure  cylinder,  at  that  portion  of  the 
sweep  of  its  piston  which  carries  it  to  the  point  of  release  of  the 
exhaust  steam. 

FIRST  EXAMPLE  (See  Fig.  10). 

One  steam  cylinder,  84  inches  diameter,  66  inches  stroke. 

Initial  steam  pressure  165  Ibs.  absolute,  or  150  Ibs.  per  gauge. 

Terminal  pressure  5  Ibs.  absolute,  or  above  perfect  vacuum. 

Ratio  of  expansion,  33  to  1. 

Point  of  cut-off,  2  inches  from  beginning  of  stroke,  no  clear- 
ance. 

Mean  effective  pressure  for  the  stroke,  22.48  Ibs. 

Area  of  the  piston,  5,541  square  inches. 

Total  mean  force  effective  on  the  piston,  124,579  Ibs. 

Gross  initial  pressure  on  the  piston,  914,265  Ibs. 

Range  of  temperature,  initial  to  terminal  pressures,  203 
degrees  Fahrenheit. 

At  200  ft.  per  minute,  755  indicated  horse  power  will  be 
developed. 

At  96  per  cent  efficiency  of  machine,  725  pump  horse 
power  would  be  shown. 

Steam  per  hour  per  diagram  would  be 6,334  Ibs. 

Steam  for  jackets  etc.  per  record,  15.45  per  cent     1,158  Ibs. 


Total  steam  per  hour 7,492  Ibs. 

Steam  per  indicated  horse  power  hour,  9.92  Ibs. 
Steam  per  pump  horse  power  hour,  10.33  Ibs. 
Duty  per  1,000  Ibs.  of  steam,  191,674,830  ft.  Ibs. 

An  engine  such  as  outlined  above  would  be  impracticable  if 
not  impossible.  The  great  range  of  temperature  indicated 
between  what  steam  would  have  at  165  Ibs.  initial  pressure  and 
5  Ibs.  terminal  pressure,  could  not  be  taken  care  of  by  a  steam 
jacket  quickly  enough  to  protect  the  working  steam  during  one 
stroke  in  any  engine  it  would  be  practicable  to  build.  And 


THE  MARIOTTE  CURVE 


53 


further,  the  great  initial  load  of  914,265  Ibs.  would  be  extremely 
difficult  to  accommodate  in  a  profitable  manner  in  an  engine  of 
the  power  indicated,  and  with  this  power  to  be  distributed 
throughout  the  machine  for  the  purpose  of  pumping  water  in  an 
acceptable  manner. 


165  Ibs.  absolute  pressuri 
150  Ibs.  Gauge  pressure. 
Initial  steam  pressure. 
Temperature  365° 


High  Pressure  Cylinder 


Range  of  Temperature  from  Initial  to  Terminal  Pressure! 
365°-  269°=96°  Pahr. 

30%  inch  Cylinder,  66   inches  Stroke 

251.67  Horse  Power  at  200  feet  piston  speed. 

M.E.P.      57.18  Ibs. 

Cut-off  =16M  inches  from  beginning  of  stroke 

Ratio  of  expansion  =  4  to  1. 


Counter  pressure 
41.25  Ibs.  absolute 


41.25  Ibs.  absolute  terminal 


269°  Temperature,  Fahr. 


41.25  Ibs.  absolute  pressure. 
26.25  Ibs.  Gauge  pressure. 


Counter  pressure 
8.25  Ibs.  absolut 
Range  of  Temperature  from  Initial  to  Term 

183°-162<5=21°  Fahr. 
Atmospheric  Line  for  Low  Pressuri 


Range  of  Temperature  from  Initial  to  Terminal  Pressures. 
269^  183°*86°  Fahr. 

63H  inch  Cylinder,  66   inches  Stroke 

M.E.P.  =  13.28  Ibs.         251.67  H.P.  at  200  feet  piston  speed. 
Cut-off—  13.2  inches  from  beginning  of  stroke 

Ratio  of  expansion  -=  5  to  1. 

8.25  Ibs.  absolute  terminal 


183°  Temperature,  Fahr. 


8.25  Ibs.  absolute  pressure,  Initial. 

|                  Low  Pressure  Cylinder 

162°  Tempera 

ure.FahrTI 

Perfect  Vacuum 
84   inch  Cylinder,  66  "inches  Stroke 
M.E.P.  =  7.49  Ibs. 

251.67  Horse  Power  at  200  fee 
Cut-off  =  40  inches  from  begi 
Ratio  <>f  expansion  =  1.65  to 

piston  speed. 
ling  of  stroke 

Fig.  11. — The  Mariotte  Curve  Through  Three  Cylinders. 

SECOND  EXAMPLE  (See  Fig.  11). 
Triple  Expansion,  or  the  Same  Work  Through  Three  Cylinders* 

High  pressure  cylinder,  30|  inches  diameter. 
Intermediate  cylinder,  63|  inches  diameter. 
Low  pressure  cylinder,  84  inches  diameter. 
All  of  66  inches  stroke. 
High  pressure  initial,  165  Ibs.  absolute. 
High  pressure  terminal,  41.25  Ibs.  absolute. 
High  pressure  effective  initial,  123.75  Ibs. 


54  PUMPING  ENGINES 

High  pressure  ratio  of  expansion,  4  to  1. 

High  pressure  point  of  cut-off,  16.5  inches  from  beginning  of 

stroke. 

High  pressure  mean  effective  pressure,  57.18  Ibs. 
Area  of  the  piston,  726  square  inches. 
Initial  load  on  piston,  119,790  Ibs. 
Total  mean  effective  force  on  piston,  41,526  Ibs. 
Range   of   temperature,   initial   to   terminal  pressures,   96 

degrees. 
At    200  ft.  per    minute,  251.67    horse    power    would    be 

developed. 


Intermediate  cylinder  initial,  41.25  Ibs.  absolute. 

Intermediate  terminal,  8.25  Ibs.  absolute. 

Intermediate  effective  initial,  33  Ibs. 

Intermediate  ratio  of  expansion,  5  to  1. 

Intermediate  point  of  cut-off,  13.2  inches  from  beginning  of 

stroke. 

Intermediate  mean  effective  pressure,  13.28  Ibs. 
Area  of  the  piston,  3,129  square  inches. 
Initial  load  on  piston,  129,070  Ibs. 
Total  mean  effective  force  on  piston,  41,526  Ibs. 
Range   of  temperature,   initial  to  terminal  pressures,   86 

degrees. 

At  200    ft.  per    minute,  251.67  horse    power  would    be 
developed. 


Low  pressure  initial,  8.25  Ibs.  absolute. 

Low  pressure  terminal,  5  Ibs.  absolute. 

Low  pressure  effective  initial,  8.25  Ibs.  absolute. 

Low  pressure  ratio  of  expansion,  1.65  to  1. 

Low  pressure  point  of  cut-off,  40  inches  from  beginning 

of  stroke. 

Low  pressure  mean  effective  pressure,  7.49  Ibs. 
Area  of  the  piston,  5,541  square  inches. 
Initial  load  on  piston,  45,713  Ibs. 


f " 

THE  MARIOTTE  CURVE  55 

Total  mean  effective  force  on  piston,  41,526  Ibs. 

Range  of  temperature,  initial  to  terminal  pressures,  21  de- 
grees. 

At  200  ft,  per  minute,  251.67  horse  power  would  be 
developed. 


Sum  of  the  power  of  all  three  cylinders,   755  indicated 

horse  power. 
At   96  per   cent  efficiency   of  machine,   725  pump  horse 

power  would  be  developed. 

Steam  per  hour  per  diagram  would  be     ....     6,334  Ibs. 
Steam  jackets  per  record,  15.45  per  cent     .    .    .     1,158  Ibs. 


Total  steam  per  hour 7,492  Ibs. 

Steam  per  indicated  horse  power  hour,  9.92  Ibs. 
Steam  per  pump  horse  power  hour,  10.33  Ibs. 
Duty  per  1,000  Ibs.  of  steam,  191,647,830  ft.  Ibs. 
Initial  load  of  all  three  pistons  together,  249,573  Ibs. 

A  comparison  of  these  two  examples  will  show  the  great 
reduction  in  the  range  of  temperature  in  any  of  the  cylinders 
of  the  triple  engine;  in  the  high  pressure  cylinder  the  range  is 
only  96  degrees  as  compared  with  203  degrees  of  the  single 
cylinder  condensing  engine;  in  the  intermediate  cylinder  the 
range  of  temperature  is  only  86  degrees,  while  in  the  low  pressure 
cylinder,  where  the  greatest  damage  to  the  steam  would  naturally 
be  done,  the  range  is  reduced  to  the  insignificant  amount  of  21 
degrees,  or  only  a  little  over  10  per  cent  of  what  it  would  be 
between  the  pressures  due  to  the  expansion  in  a  single  cylinder 
of  equal  dimensions.  And,  as  in  both  cases  the  low  pressure 
cylinder  is  next  to  the  condenser,  the  importance  of  the  change 
brought  about  by  multiple  expansion  cylinders  becomes 
apparent. 

Further  than  this  there  are  several  incidental  reasons  why 
the  three  cylinders  will  give  much  better  effects  practically 
than  one  large  cylinder  with  reference  to  the  steam  jacketing. 


56  PUMPING  ENGINES 

It  will  be  noted  that  in  the  high  pressure  cylinder  of  the  triple, 
the  range  of  temperature  due  to  the  two  pressures  of  steam, 
one  at  the  initial  of  165  Ibs.  and  the  other  at  the  terminal  of  41.25 
Ibs.  both  absolute  pressures,  is  not  only  reduced  to  less  than  half 
of  that  in  one  large  cylinder,  between  165  and  5  absolute,  but  also 
the  jacket  surface  in  the  high  pressure  cylinder  amounts  to  1.08 
square  feet  of  jacket  surface  per  cubic  foot  of  cylinder,  including 
the  area  of  one  cylinder  head,  while  the  jacket  surface  is  only 


165  Ibs.  absolute  pressure. 
150  Ibs.  Gauge  pressure. 
Initial  steam  pressure. 
Temperature  365? 


Kange  of  Temperature  from  Initial  Pressure  to  Terminal  Pressure 
365-162°»203°  Pahr. 


84"  Cylinder  x  66" Stroke 

M.E.P.  =  20  Ibs.  net. 

672  Horse  Power  at  200  feet  piston  speed. 

Cut-off  =_2"  from  beginning  of  stroke 

Ratio  of  expansion  =  33  to  1. 


Ibs.  absolute  terminal  pressure. 


Good  Practical  Vacuum 


Perfect  Vacuum  162°  Temperature,  Fahr. 

Fig.  12.  —  The  Mariotte  Curve  in  a  Single  Cylinder  in  Practice. 

.75  of  a  square  foot  of  heating  surface  for  each  cubic  foot  of 
cylinder  for  this  one  large  cylinder. 
This  tabulated  is  as  follows: 

Jacket  Surface  per  Cubic  Foot  Contents  of  Cylinder 

84  inch  cylinder,  0.75  sq.  ft. 
63  inch  cylinder,  0.92  sq.  ft. 
30  inch  cylinder,  1.80  sq.  ft. 

The  lesson  from  the  above  is  that  the  range  of  temperature 
represented  by  the  sensible  heat   of  steam  at  the  initial  and  at 


THE  MARIOTTE  CURVE 


57 


the  terminal  pressure,  in  the  high  pressure  cylinder,  is  less  than 
half  of  that  in  a  single  large  cylinder.  The  ratio  is  2.4  to  1  in 
favor  of  the  high  pressure  cylinder,  and  the  radiating  distance 
from  the  side  surfaces  to  reach  the  center  is  2.8  times  greater  in 
the  large  cylinder  than  in  the  high  pressure  cylinder.  The 


165  Ibs.  absolute  pressure. 
150  Ibs.  Gauge  pressure. 


Bange  of  Temperature  from  Initial  to  Terminal  Pressures 

365-270  =  95°  Pahr. 
30   inch  Cylinder,  66   laches  Stroke 
M.E.P.=  52.323  Ibs. 

224  Horse  Power  at  200  feet  piston  speed. 
Cut-off  =  16.96  Inches  from  beginning  of  stroke 
Ratio  ot  expansion  =  3. 89  to  1. 


2.36  Ibs.  absolute  terminal 


42.36  Ibs.  absolute 


42.36  Ibs.  absolute  pressu 
3       27.36  Ibs.  Gauge  pressure 
£  I  J-  Initial  steam  pressure. 
("Temperature  270°  Fah. 

Intermediate  Cylinder 
Counter  |ir< 
1.45  lb*.  absolute 


"Range  of  Temperature  from  Initial  to  Terminal  Pressures 

2702-  197 °=73°  Fahr. 
56   Inch  Cylinder,  66   inches  Stroke 
M.E.P.=  14.998  Ibs.       224  H.P.  at  200  feet  piston  speed. 
Cut-off  =  17.84  inches  from  beginning  of  stroke 
Ratio  of  expansion  .  5  to  1. 


J1.45  Ibs.  absolute  terminal 
197°  Temperature,  Fahr. 


Range  of  Temperature  from  Initial  to  Terminal  Pressures 

197-162°=.  35°  Fahr. 
11.45  Ibs.  absolute  pressure,  Initial.  Atmospheric  Line  for  Low  Pressure  Cylinder 


Perfect  Vacuum 


84    inch  Cylinder,  66   inches  Stroke 
M.K.P.  =  U.Sfi6  Ibs. 


224  Horse  Power  at  200  feet  piston  speed. 
Cut-off  =  28.73  Inches  from  beginning  of  stroke 
Ratio  of  expansion       2.29  to  1. 


Fig.  13. — The  Mariotte  Curve  in  a  Triple  Engine  in  Practice. 


range  of  temperature  represented  by  the  difference  in  initial  and 
terminal  pressures  in  the  intermediate  cylinder  is  less  than  half 
that  in  the  large  single  cylinder  and  with  a  greater  proportionate 
jacket  area.  And  finally  the  range  of  temperature  in  the  low 
pressure  cylinder  of  the  triple  is  only  about  one -tenth  of  that  of 
the  single  cylinder,  and  with  an  equal  amount  of  jacket  surface. 
The  work  done  in  the  water  end  of  a  pumping  engine  under  the 


58 


PUMPING  ENGINES 


foregoing  conditions  would  pump  water  as  per  the  following 
table: 


U.  8. 

GALLONS,  24  HOUBS. 

LBS.  PBESSUKE. 

10,000,000 

180 

15,000,000 

120 

20,000,000 

90 

30,000,000 

60 

THIRD  EXAMPLE  (See  Fig.  12). 
Single  Cylinder,  Straight  Condensing  Engine,  in  Practice. 

One  cylinder,  84  inches  diameter,  66  inches  stroke. 

Initial  steam  pressure  165  Ibs.  absolute,  or  150  Ibs.  per  gauge. 

Terminal  pressure  5  Ibs.  absolute,  or  above  perfect  vacuum. 

Ratio  of  expansion,  33  to  1. 

Point  of  cut-off,  2  inches  from  beginning  of  stroke,  no  clear- 
ance. 

Mean  effective  pressure  for  the  stroke,  22.48  Ibs. 

Loss  shown  by  best  practicable  vacuum,  2.48  Ibs. 

Net  mean  effective  pressure  in  one  84  inch  cylinder,  20  Ibs. 

Area  of  the  piston,  5,541  square  inches. 

Total  net  mean  effective  force  on  the  piston,  110,820  Ibs. 

Range  of  temperature  from  initial  to  terminal  pressures, 
203  degrees. 

At  200  ft.  per  minute,  672  indicated  horse  power  would  be 
developed. 

At  96  per  cent  efficiency  of  machine,  645  pump  horse  power 
would  be  developed. 

FOURTH  EXAMPLE  (See  Fig.  13). 
Triple  Expansion  Pumping  Engine  in  Practice. 

High  pressure  cylinder,  30  inches  diameter. 
Intermediate  cylinder,  56  inches  diameter. 
Low  pressure  cylinder,  84  inches  diameter. 
All  of  66  inches  stroke. 


THE  MARIOTTE  CURVE  5b 

Total  net  piston  force  as  per  Third  Example,  110,820  Ibs. 
One  third  of  110,820  Ibs.  each  piston  of  triple  engine,  36,940 

Ibs. 

High  pressure  initial,  165  Ibs.  absolute. 
High  pressure  terminal,  42.36  Ibs.  absolute. 
High  pressure  effective  initial,  122.64  Ibs. 
High  pressure  ratio  of  expansion,  3.89  to  1. 
High  pressure  point  of  cut-off,  16.96  inches  from  beginning 

of  stroke. 

High  pressure  mean  effective  pressure,  gross,  57.64  Ibs. 
Deficiency  in  practical  high  pressure  diagram,  5.317  Ibs. 
Net  mean  effective  pressure,  high  pressure  cylinder,  52.323 

Ibs. 

Area  of  the  piston,  706  square  inches. 
Total  mean  effective  force  on  high  pressure  piston,  36,940 

Ibs. 
Range  of  temperature  from  initial  to  terminal  pressures, 

95  degrees. 
At  200  ft.  per  minute,  224  horse  power  would  be  developed. 


Intermediate  cylinder,  initial  42.36  Ibs.  absolute. 

Intermediate  terminal,  11.45  Ibs.  absolute. 

Intermediate  effective  initial,  30.91  Ibs. 

Intermediate  ratio  of  expansion,  3.7  to  1. 

Intermediate  point  of  cut-off,  17.84  inches  from  beginning 

of  stroke. 

Intermediate  mean  effective  pressure,  14.998  Ibs. 
Area  of  the  piston,  2,463  square  inches. 
Total  mean  effective  force  on  piston,  36,940  Ibs. 
Range  of  temperature  from  initial  to  terminal  pressures, 

73  degrees. 
At  200  ft.  per  minute,  224  horse  power  would  be  developed. 


Low  pressure  initial,  11.45  Ibs.  absolute. 

Loss  shown  by  best  practical  vacuum,  2.48  Ibs. 


60  PUMPING  ENGINES 

Low  pressure  effective  initial,  8.97  Ibs. 

Low  pressure  terminal,  5  Ibs.  absolute. 

Low  pressure  ratio  of  expansion,  2.29  to  1. 

Low  pressure  point  of  cut-off,  28.73  inches  from  beginning 
of  stroke. 

Low  pressure  mean  effective  pressure,  gross,  9.14  Ibs.  abso- 
lute. 

Loss  shown  by  best  practicable  vacuum,  2.4733  Ibs.  absolute. 

Low  pressure  net  mean  effective  pressure,  6.6667  Ibs. 

Area  of  the  piston,  5,541  square  inches. 

Total  mean  effective  force  on  piston,  36,940  Ibs. 

Range  of  temperature  from  initial  to  terminal  pressures, 
36  degrees. 

At  200  ft.  per  minute,  224  horse  power  would  be  developed. 

Sum  of  the  powers  of  all  three  cylinders,  672  indicated 
horse  power. 

At  96  per  cent  efficiency  of  machine,  645  pump  horse  power 
would  be  shown. 

Steam  per  hour  per  diagram  would  be 6,334  Ibs. 

Steam  jackets  per  record 1,158  Ibs. 


Total  steam  per  hour 7,492  Ibs. 

Steam  per  indicated  horse  power  per  hour,  11.14  Ibs. 

Steam  per  pump  horse  power  per  hour,  11.67  Ibs. 

Duty  per  1,000  Ibs.  of  steam,  169,657,240  ft.  Ibs. 

With  10%   jacket  consumption,  the  steam  per  indicated 

horse  power  per  hour  would  be,  10.47  Ibs. 
And  the  duty  per  1,000  Ibs.  of  steam,  181,484,876  ft.  Ibs. 

NOTE.  —  This  demonstration  was  written  about  7  months  before  the 
new  record  of  181,065,943  duty  per  1,000  Ibs.  of  steam  was  made  at  St. 
Louis  in  April,  1906. 

The  raise  in  duty  between  15.45%  and  10%  of  the  total 
steam  consumed  in  the  jackets,  shows  the  importance  of  limit- 
ing the  use  of  steam  in  the  steam  jackets  to  the  lowest  needed 
.amount,  and  some  further  remarks  will  be  made  upon  this  point 
under  the  head  of  steam  jackets.  To  state  this  jacket  percen- 


THE  MARIOTTE  CURVE  61 

tage  the  other  way;  with  15.45%  of  the  total  steam  consumed 
in  the  jackets,  84.55%  would  be  used  as  working  steam  in  the 
cylinders;  and  with  10%  consumed  in  the  jackets,  the  working 
steam  would  amount  to  90%  of  the  total  used;  and  as  the  amount 
of  working  steam  would  be  about  the  same  in  any  good  case, 
it  follows  that  the  less  jacket  steam  we  can  get  along  with,  the 
less  the  total  steam  will  be  to  charge  against  the  work  done  by 
the  engine.  Then  if  by  some  marvel  all  the  steam  ordinarily 
used  in  the  jackets  could  be  saved  and  the  working  steam  in  the 
cylinders  be  kept  dry,  100%  of  the  total  steam  would  be  ex- 
pressed by  that  accounted  for  by  the  diagram,  which  in  the 
above  case  is  6,334  Ibs.  per  hour.  The  statement  then  would 
be  as  follows: 

Steam  per  indicated  horse  power  per  hour,  9.43  Ibs. 
Steam  per  ,pump  horse  power  per  hour,  9.82  Ibs. 
Duty  per  1,000  Ibs.  of  steam,  201,629,327  ft.  Ibs. 

This  apparently  marks  the  limit  for  150  Ibs.  gauge  steam 
pressure  and  the  Mariotte  curve,  and  in  this  connection  it  may 
be  of  interest  to  note  that  some  years  ago,  when  154,000,000  ft. 
Ibs.  duty  marked  the  limit  of  accomplishment,  an  eminent  pro- 
fessional authority  remarked  that  this  record  was  about  25% 
below  the  ideal  results.  And  201,629,327  discounted  25% 
amounts  to  151,221,986  duty,  which  seems  to  indicate  that  the 
reflected  light  and  the  real  light  focus  on  the  same  point  ery 
nearly. 

Further  than  this,  to  show  a  still  closer  relation  it  may  be 
observed  that  the  latest  large  pumping  engine,  of  the  vertical 
triple,  crank,  and  fly  wheel  type,  designed  for  150  Ibs.  gauge 
pressure  has  steam  cylinders  as  follows: 

High  pressure  cylinder,  30  inches  diameter. 
Intermediate  cylinder,  56  inches  diameter. 
Low  pressure  cylinder,  84  inches  diameter. 
All  with  a  stroke  of  60  inches.     . 
Capacity  per  24  hours,  15,000,000  U.  S.  gallons. 
Working  load  against  plungers,  120  Ibs. 


62  PUMPING  ENGINES 

The  dimensions  which  work  out  in  this  chapter  as  an  ideal 
engine,  with  which  to  consider  the  Mariotte  curve,  and  supposed 
to  be  of  the  vertical  triple  expansion,  crank  and  fly  wheel  type 
has  steam  cylinders  as  follows: 

High  pressure  cylinder,  30f  inches  diameter. 

Intermediate  cylinder,  63J  inches  diameter. 

Low  pressure  cylinder,  84  inches  diameter. 

All  with  a  stroke  of  66  inches. 

Capacity,  15,000,000  U.  S.  gallons  against  120  Ibs.  load. 


CHAPTER  VI 

STEAM   JACKETS 

THE  measure  of  economy  brought  about  by  the  use  of  the 
steam  jacket  applied  to  the  cylinders  of  steam  engines  has  long 
been  a  disputed  question.  But  in  all  such  matters  the  evidence 
comes  forward  slowly  on  account  of  the  many  varying  conditions 
involved,  and  the  scarcity  of  opportunities  for  making  demon- 
strations both  ways,  with  the  engine  design,  the  adaptability  of 
the  design  to -the  work,  and  other  matters  remaining  the  same. 
It  is  very  easy  to  conceive  of  a  large  and  important  engine  being 
badly  adapted  to  its  work;  or,  the  steam  jackets  on  any  sized 
engine  being  badly  proportioned  or  badly  applied,  or  badly 
supplied  with  steam,  either  too  much  steam  or  too  little.  The 
saving  of  one  pound  of  steam  per  hour  with  an  engine  of  say 
1,000  horse  power,  and  this  is  not  a  large  machine  these  days, 
means  as  per  the  following  statement : 

Steam  per  hour  supposed  to  be  saved  by  steam  jacket, 
1,000  Ibs. 

Coal  at  8  Ibs.  evaporation,  per  hour,  125  Ibs. 

Fraction  of  a  ton  of  2,000  per  10  hours,  .625. 

Coal  for  10  hours,  1,250  Ibs. 

Cost  of  .625  of  a  ton  at  $3  per  ton,  one  day  $1.87. 

Cost  of  coal  saved  for  300  days  per  year,  $562.50. 

Capital  upon  which  5%  would  be  earned,  $11,250. 
The  main  question  is  after  all,  will  a  part  of  the  steam  going 
through  the  jackets  and  a  part  going  through  the  cylinders 
result  in  the  use  of  less  total  steam  than  all  of  the  steam  going 
through  the  cylinders,  or  will  it  not? 

The  writer  has  experimented  a  good  deal  with  steam  jackets 
for  the  past  20  years,  and  distinctly  remembers  that  upon  several 


64  PUMPING  ENGINES 

occasions  when  the  jacket  steam  had  been  greatly  restricted  for 
experimental  purposes,  and  the  record  made  by  several  hours 
run,  the  steam  supply  valve  for  the  jacket  was  again  opened  up 
full  on;  whereupon  the  engine  increased  its  speed  two  or  three 
turns  per  minute.  This  being  immediately  noted  and  that  no 
other  condition  had  been  changed,  experimental  runs  were  made, 
and,  although  a  little  greater  speed  was  maintained  with  the 
increased  amount  of  steam  going  through  the  jackets,  and  a 
little  more  water  pumped,  generally  about  3  per  cent,  there  was 
a  net  loss  for  the  reason  that  the  increased  steam  let  into  the 
jackets  was  more  in  proportion  than  the  gain  in  mechanical  work; 
the  jacket  supply  was  again  cut  down  and  the  net  efficiency  rose 
at  once.  This  demonstrated  that  too  much  steam  could  be 
admitted  to  a  jacket  and  also  that  the  heat  will  do  the  work 
whether  it  goes  through  the  main  throttle  valve  into  the  work- 
ing cylinders,  or  through  the  metal  of  the  cylinders.  So  far  as 
coal  consumption,  and  therefore  the  cost  of  the  power  from  that 
item  was  concerned,  it  did  not  matter  whether  the  heat  went 
through  the  metal  and  after  bringing  the  working  steam  up  to 
the  best  point  of  efficiency,  sent  a  surplus  of  heat  into  the  exhaust 
and  into  the  traps;  or  whether  the  cut-off  was  let  out  and  steam 
followed  the  piston  to  a  little  later  point  in  the  stroke.  It  was 
also  demonstrated  that  when  the  jacket  valve  was  opened  wider, 
the  cut-off  point  had  to  be  set  back  to  keep  the  engine  down 
to  normal  speed,  and  when  the  jacket  steam  was  restricted  the 
cut-off  point  had  to  be  advanced  to  maintain  the  speed  up  to 
the  mark.  Therefore  it  follows  that  it  makes  no  difference  in 
gaining  or  reducing  speed  whether  more  or  less  steam  is  admitted 
up  to  cut-off  or  into  the  jackets,  so  far  as  each  of  these  items 
is  concerned  separately.  The  proper  combination  of  jacket  and 
cut-off  conditions  however  control  the  item  of  steam  economy. 

There  are  so  far  no  claims  that  the  steam  jacket  has  made  any 
losses  in  any  plant  at  all  adapted  to  the  work  in  hand,  and  the 
records  mostly  show  at  least  that  the  jackets  even  in  the  cases 
of  apparently  bad  showing,  pay  for  their  own  steam  and  a  little 
more,  but  whether  they  pay  for  their  existence  seems  to  be  in 


STEAM  JACKETS  65 

some  cases  doubtful  to  say  the  least.  The  steam  jacket  is  not 
a  very  costly  addition  to  a  steam  cylinder  and  the  net  saving 
does  not  have  to  be  so  very  much  to  pay  for  its  being  put  there. 
A  point  not  made  entirely  clear  so  far  with  mill  engines,  is  whether 
or  not  the  gross  wrork,  or  the  indicated  horse  power,  is  more  or 
not  without  the  jackets.  All  conclusions  with  mill  engines  have 
of  course  been  based  upon  the  indicated  power,  and  in  the  case 
of  a  dry  cylinder  with  jackets  as  against  a  damp  cylinder  with- 
out jackets,  the  former  may  furnish  a  greater  proportionate 
amount  of  useful  power;  which  means  that  with  moist  steam  in 
the  cylinder  some  perceptible  effort  may  be  necessary  upon  the 
part  of  the  engine  to  overcome  the  "laziness"  of  the  piston. 
In  mill  engines  this  is  not  an  easy  point  to  determine,  but  with 
a  pumping  engine  wherein  the  net  work  is  so  easily  measured, 
all  or  nearly  all  results  favor  the  steam  jacket.  When  Geo.  H. 
Corliss  made  his  five  cylinder  straight  condensing  pumping 
engine  for  the  city  of  Providence,  back  in  the  seventies,  his 
results  would  no  doubt  have  been  very  much  better  had  he  fitted 
the  engine  with  steam  jackets,  as  is  evidenced  by  the  enormous 
evaporation  and  high  terminal  pressure  in  the  steam  cylinders. 

A  case  in  point  is  as  follows : 

A  compound  duplex  condensing  pumping  engine  of  2,000,000 
gallons  daily  capacity  had  been  installed,  and  under  the  contract 
had  been  calculated  to  operate  without  steam  jackets.  But  to 
save  time,  and  the  making  of  new  cylinders,  a  set  of  cylinder 
castings  was  used  which  had  been  on  hand  for  some  time,  and 
which  had  steam  jackets.  The  engine  was  started  up  without 
connecting  up  the  jackets,  and,  although  the  indicated  horse 
power  seemed  to  be  ample  for  the  water  load,  and  the  steam  per 
indicated  horse  power  seemed  to  be  reasonable,  the  engine  could 
not  be  brought  up  to  speed.  In  other  words  the  steam  per 
horse  power  hour  was  all  right  but  the  apparent  mechanical  effi- 
ciency of  the  machine  was  all  wrong.  After  testing  out  for  line 
and  for  undue  friction  in  the  engine,  and  these  found  to  be  normal, 
the  steam  jackets  were  connected  up  and  the  trouble  was  over- 
come at  once. 


66  PUMPING  ENGINES 

Where  reheating  effects  are  sought  in  chimney  flues  the 
apparent  usefulness  of  the  steam  jacket  may  appear  small;  but 
if  the  heat  of  a  chimney  flue  is  applied  to  its  legitimate  work  of 
heating  feed  water  or  is  absorbed  in  making  steam  within  the 
boiler  before  reaching  the  flue,  the  net  results  might  be  better 
than  letting  such  heat  escape  from  the  boiler  and  then  attempt 
to  get  it  back  again  into  steam  on  its  passage  from  one  cylinder 
to  another  by  the  use  of  coils  in  the  boiler  flue.  The  net  profit 
of  a  steam  jacket  lies  largely  in  the  manner  in  which  the  jacket 
is  adapted  and  applied. 

In  the  modern  pumping  engine  of  high  efficiency  and  of  com- 
parative high  first  cost,  but  which  when  properly  designed  and 
built,  and  properly  adapted  to  its  task,  returns  a  very  hand- 
some profit  upon  its  excess  of  cost  over  a  cheaper  but  more 
extravagant  competitor,  it  is  sometimes  impossible  to  use  the 
high  rates  of  expansion  needed  for  desirable  results  without 
condensing  from  25%  to  40%  of  the  initial  steam  within  the 
cylinders  in  the  absence  of  steam  jackets.  Therefore,  if  we  can 
expend  say  15%  of  the  total  steam  and  save  30%  then  the  use  of 
steam  jackets  will  pay. 

To  illustrate  this,  supposing  that  a  pumping  engine  could  be 
supplied  with  7,000  Ibs.  of  steam  per  hour  from  the  boilers;  and 
that  without  steam  jackets,  say,  30%  of  the  total  steam  will  be 
condensed  within  the  cylinders.  Then  we  should  have  a  loss  of 
2,100  Ibs.  of  steam,  making  only  4,900  Ibs.  available  for  work  per 
hour.  This  would  at  the  best  record  give  472  horse  power,  and 
counting  the  lost  steam  there  would  be  a  consumption  of  14.7 
Ibs.  per  horse  power  per  hour  without  steam  jackets.  By  the 
use  of  steam  jackets  in  such  an  engine  properly  applied  and 
operated,  if  15%  of  the  total  steam  supplied  should  be  used 
in  the  jackets  and  most  all  of  the  initial  condensation  prevented, 
then  the  amount  of  steam  saved  per  hour  would  be  1,050  Ibs. 
giving  available  for  work,  5,950  Ibs.  of  steam,  which  at  the 
record  rate  per  horse  power  would  develop  573  horse  power, 
or  give  a  horse  power  for  12.2  Ibs.  of  total  steam.  The  gain  in 
power  would  be  21%  and  at  8  Ibs.  evaporation  with  coal  at  $3 


GEORGE    H.   CORLISS. 


STEAM  JACKETS  67 

per  ton  the  difference  in  cost  of  power  in  favor  of  steam  jackets 
would  be  5%  per  annum  on  $34,492.  Such  perfection  as  men- 
tioned above  would  be  very  hard  to  reach,  but  the  saving  by 
the  jackets  would  without  doubt  reach  the  net  amount  in  the 
steam  of  10%,  and  this  at  8  Ibs.  evaporation  and  with  coal  at 
$3  per  ton  would  pay  5%  per  annum  on  $22,995,  which  represents 
a  great  deal  more  than  the  difference  between  jackets  and  no 
jackets  in  the  matter  of  construction. 

Therefore  it  can  safely  be  said  that  with  pumping  engines,  at 
least  under  most  conditions,  enough  more  steam  can  be  saved  by 
the  jackets  than  the  uses  of  the  jackets  and  reheaters  call  for, 
to  make  such  practice  profitable,  especially  if  the  conditions 
are  carefully  considered  as  to  ratios  of  expansion,  steam  pres- 
sures, and  the  relation  between  the  jacket  heat  and  the  work- 
ing steam.  In  this  connection,  certain  very  high  authorities, 
both  in  this  country  and  abroad,  have  concluded  that  when 
properly  designed  and  applied,  steam  jackets  will  use  from  4% 
to  6%  of  the  total  steam  sent  to  the  engine  in  single  cylinder 
condensing  engines  under  the  ordinary  ratios  of  expansion,  and 
in  compound  and  in  triple  engines  from  9%  to  12%,  although  a 
few  cases  have  shown  as  high  a  consumption  in  the  jackets  as 
15%  of  the  total  steam  supplied  to  the  engine.  The  pumping 
engine  holding  the  world's  record  for  economy,  September  1, 
1905,  of  163,925,000  ft.  Ibs.  per  1,000,000  heat  units,  or  of  10.335 
Ibs.  of  dry  steam  per  horse  power  per  hour  condenses  in  its  jackets 
15.45%  of  the  total  steam  used.  Its  pressures  when  the  record 
was  taken  were  as  follows: 

Steam  at  throttle,  185  Ibs.  gauge. 
Steam  in  first  receiver,  31  Ibs.  gauge. 
Steam  in  second  receiver,  11  Ibs.  absolute. 
Steam  in  high  pressure  jacket,  185  Ibs.  gauge. 
Steam  in  intermediate  jacket,  74  Ibs.  gauge. 
Steam  in  low  pressure  jacket,  5  Ibs.  gauge. 

As  a  result  of  many  records  the  fact  seems  to  be  that  single 
cylinder  condensing  engines  will  save  from  2  to  3  times  net,  the 


68  PUMPING  ENGINES 

amount  of  steam  used  in  the  jackets;  compound  engines  about 
twice  as  much  net,  the  amount  of  steam  used  in  the  jackets;  and 
triples  about  as  much  net,  as  the  jackets  use. 

The  conditions  of  pressure  under  the  above  mentioned  saving 
of  steam  by  the  use  of  jackets,  is  laid  down  as  follows  by  the 
British  Board  of  Admiralty: 


TYPE  OF  ENGINE. 

GAUGE  PRESSURE. 

Single  Cylinder  condensing   

90  Ibs. 
120 
160 
225 

initial. 

Triple  condensing 

Quadruple  condensing               

Rotative  speed  does  not  seem  to  affect  the  case  if  the  proper 
conditions  otherwise  exist.  There  are  records  of  compound 
engines  at  250  revolutions  per  minute,  using  6  per  cent  of  the 
total  steam  in  the  jackets  and  saving  9  per  cent  net;  or  the 
jackets  use  6  per  cent  of  the  total  steam  sent  to  the  engine  when 
jackets  are  used,  and  save  15  per  cent  over  what  the  engines 
will  do  without  steam  jackets,  thus  making  a  net  economy  or 
profit  by  the  jackets  in  that  case  of  9  per  cent.  The  entire 
desirability  of  steam  jackets  seems  to  be  a  question  of  their 
uselessness  or  their  usefulness,  and  these  qualities  r.rc  in  turn 
dependent  upon  their  design  and  arrangement.  It  ic  obvious 
that  well  jacketed  heads  expose  a  generous  area  of  surface  in 
proportion  to  the  rather  limited  body  of  the  initial  steam  and 
will  have  a  more  decided  effect  in  furnishing  latent  heat  for 
entrained  water,  than  merely  jacketing  the  sides  which  are  not 
exposed  until  a  goodly  portion  of  the  stroke  has  been  accomp- 
lished; and  after  all  the  prevention  of  initial  condensation  is 
the  most  valuable  use  of  a  jacket,  for  one  simple  reason  among 
others,  that  is,  if  the  steam  starts  dry,  the  constantly  falling 
pressure  due  to  expansion  presents  no  tendency  to  moisture 
which  cannot  be  instantly  taken  care  of  under  the  lowering 
pressure  and  the  constantly  high  temperature  within  the 
cylinder  and  jackets. 


STEAM  JACKETS  69 

With  a  30  inch  cylinder  for  example,  when  the  piston  has 
moved  2|  inches  from  the  beginning  of  the  stroke,  the  initial 
steam  will  represent  about  one  cubic  foot  of  quantity,  while  with 
a  jacketed  head  the  heating  area  of  the  head  will  represent  about 
5  square  feet  of  surface. 

With  jacketed  sides  and  with  no  head  jackets,  the  same  amount 
of  motion  of  the  piston  would  give  one  cubic  foot  of  steam  to  be 
heated  and  a  little  over  1J  square  feet  of  heating  surface.  And 
besides  this,  with  the  jacketed  head  the  radiation  would  have 
to  go  2£  inches  only  to  completely  penetrate  the  steam,  while 
with  the  side  jacket  the  radiation  would  have  to  go  15  inches 
to  reach  the  entire  body  of  steam.  These  results  would  be  more 
or  less  modified  by  the  admission  ports  and  the  heat  of  the  incom- 
ing steam,  but  this  would  be  robbing  Peter  to  pay  Paul,  and 
Paul's  share  would  not  represent  the  full  robbery  of  Peter,  either. 

Some  of  the  apparent  inconsistencies  of  the  reported  steam 
consumption  in  the  jackets  might  possibly  be  explained  by  just 
such  differences  in  the  application  of  steam  jackets.  Such  jackets 
are  of  all  kinds  and  qualities,  according  to  the  more  or  less  suc- 
cessful attempts  of  the  designer;  a  high  efficiency  of  jacket  from 
a  well  jacketed  cylinder  head,  .working  upon  the  initial  steam 
at  the  instant  of  its  admission  and  near  the  commencement  of 
the  stroke,  wherein  a  comparatively  limited  area  is  giving  a 
highly  useful  effect,  may  result  in  the  use  of  a  very  moderate 
percentage  of  the  total  steam,  but  counting  heavily  in  the  general 
economy  of  the  engine;  while  indifferently  jacketed  heads  and  a 
thoroughly  jacketed  barrel,  or  a  well  jacketed  barrel  and  no 
jackets  at  the  heads,  might  very  easily  result  in  a  great  deal  of 
jacket  condensation  with  no  very  great  gain  in  the  general 
economy  of  the  engine.  Records  show  all  the  way  from  1  per 
cent  to  20  per  cent  of  the  total  steam  used  in  the  jackets 
according  to  the  design  of  the  engine,  the  design  and  application 
of  the  jackets,  and  the  hundred  and  one  conditions  under  which 
the  entire  outfit  might  be  made  to  operate. 

It  must  always  be  borne  in  mind  that  the  lower  the  grade  of 
refinement  in  design  in  a  steam  engine  the  easier  it  is  to  improve 


70  PUMPING  ENGINES 

its  operation.  And  the  higher  the  degree  of  refinement  the  more 
difficult  and  also  the  closer  must  the  conditions  be  accommo- 
dated. With  an  engine  taking  steam  full  stroke,  and  regulating 
its  operation  by  raising  or  lowering  the  initial  pressure,  it  is 
already  working  under  about  the  worst  conditions  it  can,  and 
damage  to  its  economy  or  an  increase  in  its  efficiency  is  rather 
difficult  to  accomplish  without  some  departure  from  its  scope  or 
plan.  By  applying  a  cut-off  to  such  an  engine,  an  immediate 
improvement  is  observed,  but  this  is  accompanied  by  the  fact 
that  the  load  must  be  adjusted  within  certain  limits  in  order 
that  the  best  results  may  be  obtained.  Now,  compound  this 
cut-off  engine,  and  a  still  greater  improvement  is  obtained,  but  a 
still  closer  line  must  be  drawn  for  its  operation  and  manipulation. 
Then  make  it  a  triple  expansion  engine,  and  the  lines  lie  still 
closer  to  conditions  for  satisfactory  work.  Again,  make  the 
engine  quadruple  expansion,  and  a  still  more  exacting  adapta- 
tion is  needed  for  the  best  work. 

With  steam  jacketing,  after  the  cut-off  and  expansion  has 
been  introduced,  the  greatest  gain  is  perceptible  with  the  single 
cylinder  cut-off  engine,  when  the  range  of  temperature  repre- 
sented by  the  initial  and  terminal  pressures  is  the  greatest  within 
one  cylinder.  And,  as  the  multiple  grade  of  the  engine  rises, 
to  compound,  to  triple,  and  to  quadruple,  so  that  for  any  certain 
aggregate  rate  of  expansion  the  range  of  temperature  in  any  one 
cylinder  becomes  less  and  less,  the  advantages  of  steam  jacketing 
gradually  decrease,  but  with  the  higher  ratios  of  expansion, 
especially  in  pumping  engines,  where  the  net  work  and  its  relation 
to  the  indicated  horse  power  can  be  so  closely  watched  and  noted, 
it  has  so  far  at  least  been  deemed  necessary  for  acceptable  results. 

In  making  a  comparison  in  the  matter  of  steam  jacket  value 
and  price  of  a  pumping  engine,  the  following  will  be  instructive 
in  a  practical  consideration  of  the  subject: 

Supposing  the  contract  price  of  a  triple  expansion  pumping 
engine  of  the  highest  type  of  efficiency  as  shown  in  regular 
practice,  to  be,  say,  $93,090  ready  for  service.  The  engine  to  be 
of  750  indicated  horse  power,  and  to  be  able  to  develop  a  horse 


STEAM  JACKETS 


71 


power  with  the  consumption  of  10.50  Ibs.  of  steam  per  hour 
including  jackets,  making  7,875  Ibs.  of  steam  per  hour.  Also 
supposing  that  the  jackets  used  10%  of  the  total  steam,  leaving 
7,087.5  Ibs.  of  steam  per  hour  as  the  quantity  required  for  con- 
sumption within  the  cylinders.  Then  upon  this  basis,  allowing 
that  without  steam  jackets,  the  moderate  amount  of  20%  is 
taken  for  condensation  within  the  cylinders,  there  would  be 
required  8,834  Ibs.  of  steam  per  hour  if  jackets  were  not  used, 
instead  of  the  above  mentioned  7,875  Ibs.  Then  at  the  practical 
everyday  evaporation  under  150  Ibs.  steam  pressure  of  8  to  1 
the  difference  in  coal  would  be  1.43  tons  per  day  of  24  hours, 
many  of  such  engines  generally  running  24  hours  per  day.  At 
S3  per  ton  this  will  capitalize  at  $31,337  at  5%  per  annum. 
This  amount  deducted  from  the  price  of  $93,000  for  the  jacketed 
engine,  will  produce  $61,663,  which  is  a  price  very  much  below 
the  cost  and  value  of  an  unjacketed  engine  of  otherwise  equal 
quality,  design  and  capacity. 

There  is  a  jacket  record  in  a  well  established  case,  involving 
what  might  be  called  modern  practice,  and  of  very  recent  years, 
as  low  as  9J%  and,  as  indicating  the  important  effect  of  steam 
jacket  efficiency  in  proportion  to  steam  used  in  the  jackets,  the 
following  table  of  steam  per  indicated  horse  power  per  hour  and 
of  duties  is  given.  A  practical  demonstration  was  made  in  a 
recent  case  bearing  directly  upon  this  portion  of  the  subject 
which  clearly  illustrates  the  importance  of  not  using  too  much 
steam  in  the  jackets.  The  duty  of  a  certain  pumping  engine 
had  not  been  satisfactory,  but  a  strong  belief  existed  that  better 
results  could  be  shown  if  the  machine  was  operated  under  more 
appropriate  conditions.  When  first  examined,  the  engine  was 
running  at  normal  speed  with  the  throttle  valve  wide  open  and 
the  pressures  as  follows : 


STEAM  AT 
THROTTLE, 
GAUGE. 

FlBST 

RECEIVER, 
GAUGE. 

SECOND 
RECEIVER, 
GAUGE. 

HIGH 
PRESSURE 
JACKET, 
GAUGE. 

INTER- 
MEDIATE 
JACKET, 
GAUGE. 

Low 
PRESSURE 
JACKET, 
GAUGE. 

155 

35 

4 

152 

70 

27 

72 


PUMPING  ENGINES 


The  first  thing  done  was  to  ascertain  the  amount  of  steam 
being  condensed  in  the  jackets,  and  at  the  same  time  run  a  short 
duty  test  per  1,000  Ibs.  of  steam.  The  jacket  steam  was  found 
to  be  about  18%  including  receiver  coils,  which  was  at  once 
considered  to  be  entirely  too  high.  Then  after  some  careful 
experimenting,  and  several  tests  run  under  different  conditions, 
the  final  test  for  duty  was  carried  out,  and  the  best  results  of 
which  the  engine  seemed  capable  were  obtained  with  the  press- 
ures as  follows: 


STEAM  AT 
THROTTLE, 
GAUGE. 

FIRST 
RECEIVE  K, 
GAUGK. 

SECOND 
RECEIVER, 
GAUGE. 

HIGH 
PRESSURE 
JACKET, 
GAUGE. 

INTER- 
MEDIATE 
JACKET, 
GAUGE. 

Low 
PRESSURE 
JACKET, 
GAUGE. 

151 

36 

4* 

85 

15 

2 

The  following  is  the  table  referred  to,  showing  the  effects  of 
an  increasing  consumption  of  steam  within  the  jackets  brought 
about  presumably  by  different  adaptations  of  the  steam  jackets 
to  their  work,  some  more  effective  than  others.  The  table  is 
based  upon  one  set  of  conditions  only,  and  are  150  gauge  pressure, 
33  expansions,  5  Ibs.  absolute  terminal,  and  the  consumption  per 
hour  of  the  working  steam  of  6,334  Ibs.  within  the  cylinders, 
giving  672  indicated  horse  power.  It  must  be  plain  that  the 
lower  the  amount  of  jacket  steam  with  which  the  work  can  be 
done,  the  nearer  100%  will  be  the  working  steam,  and  the  higher 
the  duty  will  be  per  1,000  Ibs.  of  steam  consumed,  including 
jackets  and  receiver  coils. 


PERCENTAGE  OF 
TOTAL  STEAM  USED 
IN  THE  JACKETS. 

STEAM  PER  HOUR  PER 
INDICATED  HORSE  POWER 
INCLUDING  JACKETS,  ETC. 

MAIN  PUMP  DUTY  PER  1,000 
LBS.  OF  STEAM. 

9 

10.28 

183,503,243 

10 

10.47 

181,484,876 

11 

10.59 

179,510,607 

12 

10.71 

177,737,881 

13 

10.83 

175,531,915 

14 

10.96 

173,380,035 

15 

11.08 

171,429,437 

16 

11.25 

169,230,796 

STEAM  JACKETS  73 

There  is  one  very  important  point  to  be  recognized  in  the 
employment  of  the  steam  jacket,  and  that  is,  when  the  cut-off 
valve  closes  and  the  working  steam  is  shut  within  the  cylinder, 
this  working  steam  is  completely  beyond  reach  of  direct  manipu- 
lation, so  far  as  saving  and  returning  to  the  boiler  any  part  or 
portion  of  its  heat  or  substance.  It  is  beyond  reach  and  must 
go  its  way  for  better  or  for  worse.  But  with  a  steam  jacket, 
after  the  steam  in  the  jacket  has  given  up  sufficient  heat  to  the 
cylinder  walls,  and  through  these  walls  to  the  working  charge  of 
steam  within,  the  residue  of  hot  wrater,  or  whatever  remains,  may 
be  returned  to  the  boiler,  with  the  satisfaction  that  it  has  only 
given  up  whatever  has  been  useful,  and  the  remainder  or  unused 
portion  is  still  on  hand  for  future  usefulness. 

When  it  began  to  be  comprehended  that  higher  steam  press- 
ures and  higher  ratios  of  expansion  appeared  to  be  the  road  to 
higher  duty,  the  way  seemed  clear.  But  as  usual,  new  difficulties 
loomed  up;  in  time  to  be  cleared  away  in  their  turn.  Among 
these  troubles  were  higher  ranges  of  temperature  within  the 
steam  cylinder,  although  at  first  not  understood;  and  a  very  un- 
equal distribution  of  impulse  and  working  strains  from  the  great 
difference  between  the  initial  and  the  terminal  steam  pressures. 
Active  forces  in  nature  seek  to  produce  equilibrium,  or,  in  other 
words,  a  balance;  and  taking  advantage  of  these  efforts  is  just 
where  mankind  turns  such  forces  to  practical  account  and  use- 
fulness. Water  on  top  of  a  hill  will  run  down  until  a  general 
level  is  reached  and  rest  obtained,  and  we  all  know  what  man 
does  with  water  going  from  a  higher  to  a  lower  level.  Different 
degrees  or  different  forces  of  heat,  so  to  speak,  in  different  parts 
of  the  same  substance  will  endeavor  to  bring  the  entire  mass  to  a 
balanced  temperature  or  uniformity  of  heat  throughout  the 
mass. 

Initial  or  incoming  steam  within  a  cylinder,  at  a  gauge  press- 
ure of  150  Ibs.,  or  165  absolute  pressure,  the  latter  pressure  ob- 
tained by  adding  to  the  gauge  pressure,  the  atmospheric  pressure 
of  15  Ibs.,  has  a  temperature  of  365  degrees  by  the  Fahrenheit 
thermometer.  And  if,  after  the  cut-off  valve  has  closed,  the 


74  PUMPING  ENGINES 

steam  should  be  expanded  down  to  5  Ibs.  absolute  pressure,  or 
5  Ibs.  above  a  perfect  vacuum,  equivalent  to  a  little  more  than 
19  inches  of  vacuum,  then  the  temperature  of  steam  at  the  lower 
pressure  in  the  absence  of  extra  heat  would  be  162  degrees,  or 
203  degrees  below  the  temperature  of  the  initial  or  incoming 
steam  at  the  next  stroke  of  the  piston.  In  the  absence  of  some 
adequate  means  for  preserving  the  heat  of  the  cylinder  walls,  as, 
for  example,  a  steam  jacket,  it  is  not  difficult  to  perceive  that  a 
great  deal  of  condensation  in  the  initial  steam  would  take  place, 
and  that  the  actual  temperature  of  the  cylinder  walls  will  be 
somewhere  at  a  point  between  the  two  extremes  of  temperature, 
much  below  and  very  damaging  to  the  initial  steam,  on  account 
of  the  high  temperature  of  the  incoming  steam,  and  the  natural 
tendency  of  heat  towards  striking  a  balance  of  temperature  in  all 
parts  of  the  same  mass. 

To  illustrate  this  action  of  the  expansion  of  steam  and  the 
difference  between  the  initial  and  terminal  temperatures  within 
an  engine  cylinder,  reference  is  made  to  Fig.  14  which  represents 
a  complete  or  absolute  pressure  of  165  Ibs.,  equivalent  to  a  gauge 
pressure  of  150  Ibs.  expanding  to  33  times  its  original  volume, 
and  down  to  a  terminal  pressure  of  5  pounds  above  a  perfect 
vacuum.  Or  from  165  absolute  down  to  5  absolute,  and  thus 
indicating  a  range  of  temperature  of  203  degrees  if  such  condi- 
tions could  be  maintained  within  a  steam  cylinder  after  the 
closing  of  the  cut-off  valve.  Now  if  the  temperature  of  the 
cylinder  walls  could  follow  that  of  the  inclosed  steam  on  the 
downward  grade,  and  finish  with  the  expansion  of  the  steam  at 
162  degrees,  of  course,  as  already  pointed  out,  the  incoming 
steam  at  365  degrees  would  suffer  severely  from  condensation 
when  entering  the  cylinder  with  its  walls  at  162  degrees,  and 
this  would  take  place  at  every  successive  stroke  of  the  piston, 
thus  robbing  the  operation  of  expansion  of  a  great  deal  of  its 
natural  advantages.  The  temperature  of  the  cylinder  walls, 
however,  would  never  get  down  to  162  nor  up  to  365,  but 
without  outside  aid  from  auxiliary  heat  would  strike  a  sort  of 
fluctuating  balance  somewhere  between  the  two  temperatures; 


STEAM  JACKETS  75 

• 

rising  and  falling  in  the  neighborhood  of  the  average  temper- 
ature at  each  stroke,  and  reevaporating  a  great  deal  of  the 
water  of  condensation  towards  the  finish  of  the  stroke. 

Considering  this  rather  extreme  illustration  of  the  effects  of 
steam  expansion,  it  would  not  take  a  great  deal  of  experimenting 
to  determine  just  about  where  the  practical  and  useful  limits  of 
high  pressure  and  ratio  of  expansion  were  to  be  found  with  steam 
used  in  an  ordinary  cylinder  without  steam  jackets  or  some 
other  means  of  maintaining  heat  in  the  cylinder  walls.  This 


11  at  165  Ibs.  absolute  pressuic 


33  Expansions. 

Range  of  temperature  between  steam  at  165  Ibs.and  5  Ibs.  absolute  is  203° Pah. 

Mean  effective  pressure  22.48  Ibs.  absolute. 


Temperature  162"Fahr. 

Fig.  14.  —  The  Mariotte  Curve  showing  Eange  of  Temperature. 

would  probably  be  with  an  initial  pressure  of  about  80  Ibs.  per 
gauge  and  with  about  4  expansions  within  any  one  cylinder. 
But  even  with  steam  jacketing,  with  the  tremendous  range  of 
temperature  of  203  degrees  called  for  by  the  differences  of  pres- 
sure for  33  expansions,  a  good  deal  of  condensation  and  consequent 
loss  would  practically  take  place  in  such  work,  and  this  drives 
home  the  argument  that  the  higher  the  number  of  cylinders,  the 
lower  the  ratio  of  expansion  in  one  cylinder  and  the  less  effective 
is  steam  jacketing,  while  such  an  attempted  range  as  203  degrees 
presents  the  most  profitable  field  for  the  steam  jacket  operation. 
To  more  fully  illustrate  this  action,  a  comparison  has  been  made 


76  t    PUMPING  ENGINES 

in  Chapter  V  in  which  theMariotte  curve  is  rather  fully  explained. 
This  comparison  is  made  between  expanding  33  times  in  one 
cylinder,  and  expanding  33  times  through  three  cylinders  as 
exemplified  in  the  present  day  triple  expansion  pumping  engine. 
And  the  comparison  for  convenience'  sake  is  made  with  the  idea 
that  perfect  vacuum  is  obtained  within  the  single  cylinder  and 
within  the  low  pressure  cylinder  of  the  triple  engine,  and  it 
is  also  assumed  in  both  cases  that  all  of  the  working  steam  is 
accounted  for  by  the  diagrams. 

An  interesting  experience  by  the  writer  will  fit  in  here  in  con- 
nection with  the  heat  of  cylinder  walls.  A  non-condensing,  non- 
jacketed  vertical  Corliss  engine,  built  by  the  parent  company, 
was  being  experimented  with  for  compression;  the  cylinder 
was  28  X  60,  the  engine  making  50  revolutions  per  minute. 
A  second  eccentric  had  been  fitted  to  this  engine  so  as  to  secure 
independent  adjustment  for  the  exhaust  valves  and  obtain  any 
desired  amount  of  exhaust  lead  and  compression  without  inter- 
fering with  the  range  of  cut-off  or  the  operation  of  the  induction 
valves  in  any  manner.  In  a  word,  so  that  both  admission  and 
exhaust  valves  could  be  adjusted  to  the  best  point  of  efficiency 
without  interfering  with  each  other.  The  initial  steam  shown 
by  the  indicator  was  85  Ibs.  per  gauge;  the  point  of  cut-off 
was  just  about  20  inches  from  the  beginning  of  the  stroke;  the 
counter  pressure  was  3  Ibs.  per  gauge.  The  indicator  was 
attached,  and  after  some  experimenting  with  the  eccentric  for 
the  exhaust  motion,  the  rest  of  the  compression  adjustments 
were  made  by  lengthening  or  shortening  the  exhaust  valve 
radius  rods,  the  jam  nuts  being  kept  loose  and  the  rods  turned 
either  way  as  the  demand  called,  after  each  indicator  card  was 
taken.  It  was  found  that  45  Ibs.  was  about  the  limit  of  com- 
pression without  disturbance  in  the  diagram,  and  when  45  Ibs. 
was  reached  in  the  compression  curve  a  small  dot  appeared 
where  the  indicator  paused  for  an  instant  before  the  admission 
line  showed  that  the  induction  valve  was  open.  By  persisting 
in  the  attempt  at  more  compression  than  45  Ibs.,  a  hook,  in  the 
line  formed  where  the  compression  and  admission  lines  joined, 


STEAM'  JACKETS  77 

began  to  appear;  and  when  the  exhaust  valve  was  adjusted 
beyond  a  certain  point  of  closure,  the  compression  stopped 
and  a  slight  drop  took  place  which  met  the  admission  line, 
thus  forming  from  the  bottom  of  the  card,  first  a  most  beauti- 
ful compression  curve  up  to  45  Ibs.  gauge  pressure,  then  a  drop 
hook  covering  a  range  of  about  4  Ibs.,  and  then  the  admission 
line  took  up  the  work  and  went  up  to  the  initial  pressure. 
Hundreds  of  experiments  were  tried  and  all  sorts  of  changes 
rung  upon  the  diagrams.  The  compression  curve  could  be 
made  to  glide  smoothly  into  the  admission  line  at  just  about 
45  Ibs.  pressure;  then  lengthening  the  radius  rods,  the  small 
dot  made  by  the  pausing  pencil  would  begin  to  appear;  this 
dot  would  grow  in  size  and  finally  develop  into  a  slight  off-set 
in  the  diagram;  then  the  hook  downwards  would  begin  to 
appear;  and  finally  the  diagram  would  be  repeated  many  times 
unchanged  as  the  conditions  were  established  with  the  exhaust 
valve  closing  at  an  earlier  point  than  the  temperature  of  the 
cylinder  walls  would  support  the  compressed  steam.  This 
operation  could  be  reversed  and  the  downward  hook  sent  back 
into  a  dot;  this  dot  gradually  diminishing  as  the  radius  rods 
were  adjusted  shorter  and  shorter;  until  finally  upon  the  re- 
verse experiment  the  smooth  compression  curve  died  out  into 
the  admission  line  as  the  incoming  steam  sent  the  pressure 
up  to  the  initial  point. 
The  temperatures  were  as  follows : 

Initial  steam,  gauge  pressure,  327°. 
Counter  pressure,  3  Ibs.  above  atmosphere,  220°. 
Top  of  perfect  compression  curve,  45  Ibs.  gauge,  292°. 
Top  of  curve  with  hook,  49  Ibs.  gauge,  296°. 

This  seems  to  indicate,  after  45  Ibs.  was  reached,  which 
represents  a  temperature  in  the  steam  of  292  degrees,  that  the 
limits  of  the  temperature  of  the  cylinder  walls  had  been  also 
reached;  and  although  the  great  abundance  of  work  available 
carried  the  pressure  up  4  Ibs.  before  the  formation  of  compressed 
steam  was  stopped  and  representing  a  top  limit  of  temperature 


78  PUMPING  ENGINES 

of  296  degrees,  the  temperature  of  the  iron  was  probably  very 
close  to  292  degrees;  or  between  6%  and  7%  above  the  half  way 
point  from  terminal  up  to  initial. 

If  this  evidence  as  to  cylinder  temperature  holds  substantially 
correct  under  most  other  conditions,  then  in  the  examples  set 
forth  in  Chapter  V  the  initial  and  cylinder  temperatures  would 
be  as  follows: 

High  pressure  cylinder;  no  steam  jackets. 

Initial  steam  temperature,  365°. 

Cylinder  temperature,  321°. 
Intermediate  cylinder;  no  steam  jackets. 

Initial  steam  temperature,  270°. 

Cylinder  temperature,  238°. 
Low  pressure  cylinder;  no  steam  jackets. 

Initial  steam  temperature,  202°. 

Cylinder  temperature,  174°. 

If  these  relations  of  temperature  between  steam  and  iron  hold 
good  in  most  cases,  it  shows  how  easy  it  would  be  to  use  too 
much  steam  in  the  jackets,  and  also  illustrates  the  fact  that  if 
the  jackets  are  not  arranged  to  get  hold  of  the  initial  steam 
instantly  and  dry  it  out,  they  will  be  extremely  likely  to  do  a 
great  deal  of  useless  work. 


CHAPTER   VII 
COAL   DUTY   OF   PUMPING   ENGINES 

THE  coal  duty  of  a  pumping  engine  is  a  term  which,  although 
not  strictly  correct  and  scientific,  has  nevertheless  gotten  to  be 
such  a  widely  employed  expression,  that  it  has  come  to  be  used 
as  a  technical  way  of  stating  the  amount  of  work  actually  realized 
in  pounds  of  water  raised  against  the  head  with  the  consumption 
of  each  100  Ibs.  of  coal.  It  is  really  the  duty  of  the  plant;  and 
the  economic  coal  duty  actually  realized  by  a  pumping  plant, 
expressed  in  foot  pounds  of  work  done  per  100  Ibs.  of  coal  burned, 
is  influenced  by  several  items  apart  and  aside  from  the  quali- 
fications of  the  pumping  engine  doing  the  work.  Prominent 
among  these  items  are :  the  efficiency  of  the  boilers  or  the  ability 
of  the  boilers  to  use  the  heat  given  out  by  the  burning  coal;  the 
actual  amount  of  heat  possible  to  obtain  from  the  coal  by  its 
combustion,  involving  the  number  of  heat  units  possible  to  obtain 
from  any  certain  kind  of  coal;  the  skill  of  the  firemen,  or  the 
efficiency  of  the  mechanical  stokers;  the  draught  in  the  chimney 
and  the  proper  manipulation  of  the  damper;  the  cleanliness 
and  good  order  of  the  plant  generally. 

As  boilers  go,  72%  efficiency  represents  very  good  work.  That 
is  to  say:  whatever  the  utmost  number  of  heat  units  it  may  be 
possible  to  obtain  by  analysis  of  the  coal,  or,  whatever  the  utmost 
number  of  heat  units  may  be,  which  the  coal  is  capable  of  giving 
out  under  complete  combustion,  if  the  boiler  can  produce  under 
the  actual  working  conditions,  between  the  temperatures  of  the 
feed  water  and  the  working  steam,  a  quantity  of  steam  which 
by  its  contained  heat  will  represent  72%  of  the  total  heat  of  the 
combustion  of  the  coal  burned,  then  such  boilers  are  doing  pretty 
good  work.  There  are  records  as  high  as  81%  efficiency;  and 

79 


80  PUMPING  ENGINES 

with  the  assistance  of  economizers  in  the  back  flue,  to  give  waste 
heat  to  the  feed  water  before  it  enters  the  boiler,  even  so  high  as 
86%  efficiency  has  been  recorded.  But  the  higher  efficiencies 
as  a  rule  represent  a  much  higher  cost  of  boiler  than  a  72% 
efficiency  boiler,  and  this  brings  into  the  account  the  balance 
between  the  interest  on  the  extra  cost  of  boiler  and  the  value  of 
the  coal  saved  by  the  higher  efficiency.  It  is  the  old  argument 
in  another  form  between  the  high  and  low  duty  engines  at  a 
higher  or  a  lower  first  cost.  That  plant  \vill  pump  water  under 
its  own  circumstances,  for  the  least  cost  in  money  per  million 
gallons  sent  up  the  hill,  which  is  the  best  adapted  to  its  surround- 
ing conditions,  including  the  cost  of  coal;  and  the  real  office  of 
the  expert  is  to  make  such  adaptations  before  the  plant  is  built, 
if  he  gets  a  chance,  rather  than  to  endeavor  to  make  impossible 
ends  meet  after  the  plant  is  built  wrong. 

The  bearing  of  the  practical  boiler  efficiency,  and  the  heat 
units  of  the  coal,  may  be  seen  more  clearly  by  the  aid  of  a  few 
figures  from  actual  cases;  and  men  who  run  pumping  engines, 
who  fire  boilers,  and  who  make  and  sell  boilers,  can  readily 
perceive  where  the  limits  of  what  can  really  be  done  are  situated. 

First  Case: 

Boiler  efficiency  72%  of  the  heat  of  the  coal. 
Temperature  of  the  feed,  150°. 
Working  pressure  per  gauge,  150  Ibs. 
Units  of  heat  per  pound  of  coal,  14,360. 

Then  the  boiler  would  turn  into  steam  72%  of  14,360',  which 
means  that  there  are  10,339.2  heat  units  available  for  steam  per 
pound  of  coal  burned,  and  of  course  this  72%  efficiency  includes 
the  furnace  as  well  as  the  boiler. 

The  range  of  heat  units  between  150°  feed  and  150  Ibs.  steam 
pressure  is  as  follows: 

150°  feed;  heat  units  per  pound  above  32° 119.3 

150  Ibs.  steam  pressure,  gauge  above  32°     1,193.5 

Then  the  heat  units  given  by  the  boiler  to  each  pound  of  steam 


I 
COAL  DUTY  OF  PUMPING  ENGINES  81 

produced,  that  is,  one  pound  of  water  evaporated  into  steam,  is 
1,074.2,  or  in  even  numbers  say,  1,074  heat  units  to  be  given  up 
to  make  each  pound  weight  of  steam  with  feed  at  150°  and  into 
steam  at  150  Ibs.  pressure  per  gauge. 

Then  the  dry  steam  possible  to  be  produced  per  pound  of  coal 
under  the  above  mentioned  conditions  would  be  at  72%  efficiency 
of  boiler  and  furnace,  9.63  Ibs. 

And  this  shows  that  between  96%  and  97%  of  the  duty  per 
1,000  Ibs.  of  steam  would  be  realized  as  coal  duty  of  the  pumping 
engine.  Or,  if  the  duty  happened  to  be,  say,  140,000,000  ft.  Ibs. 
per  1,000  Ibs.  of  steam  used  by  the  engine,  then  the  actual  coal 
duty  would  be  96%  of  the  steam  duty,  or  134,400,000  ft.  Ibs.  per 
100  Ibs.  of  coal,  which,  although  something  of  a  margin  below 
the  steam  duty,  would  be  an  exact  equivalent  under  the 
circumstances. 

Second  Case: 

Boiler  efficiency  68%  of  the  heat  of  the  coal. 

Temperature  of  the  feed,  150°. 

Working  pressure  per  gauge,  150  Ibs. 

Units  of  heat  per  pound  of  coal,  13,500. 
Then  the  boiler  would  turn  into  steam  68%  of  13,500,  which 
means  that  there  are  9,180  heat  units  available  for  steam  per 
pound  of  coal  burned,  and  of  course  this  68%  efficiency  includes 
the  furnace  as  well  as  the  boiler. 

The  range  of  heat  units  between  150°  feed  and  150  Ibs.  steam 
pressure  is  as  follows: 

150°  feed;  heat  units  per  pound  above  32° 119.3 

150  Ibs.  steam  pressure,  gauge  above  32° 1,193.5 

Then  the  heat  units  given  by  the  boiler  to  each  pound  of  steam 
produced,  that  is,  one  pound  of  water  evaporated  into  steam, 
is  1,074.2,  or  in  even  numbers  say,  1,074  heat  units  to  be  given  up 
to  make  each  pound  weight  of  steam  with  feed  at  150°  and  into 
steam  at  150  Ibs.  pressure  per  gauge. 

Then  the  dry  steam  possible  to  be  produced  per  pound  of  coal 


82  PUMPING  ENGINES 

under  the  above  mentioned  conditions  would  be  at  68%  efficiency 
of  boiler  and  furnace,  8.55  Ibs. 

And  this  shows  that  85.5%  of  the  duty  per  1,000  Ibs.  of  steam 
would  be  realized  as  coal  duty.  Or,  if  the  duty  happened  to  be 
140,000,000  ft.  Ibs.  per  1,000  Ibs.  of  steam,  used  by  the  engine, 
then  the  actual  coal  duty  of  the  plant  would  be  119,700,000  ft. 
Ibs.  per  100  Ibs.  of  coal,  which  looks  to  be  very  much  less  than 
the  steam  duty,  but  which  is  an  exact  equivalent  under  the 
circumstances. 

Therefore  it  will  be  seen  that  every  change  in  the  number  of 
heat  units  possible  to  derive  from  combustion  of  the  different 
values  of  coal,  and  every  change  in  the  practical  efficiency  of  the 
boilers  in  every-day  operation,  in  the  hands  of  the  men  who 
operate  them,  marks  a  difference  in  the  observed  coal  duty  of  the 
plant;  and  although  these  differences  could  be  tabulated  so  as 
to  cover  a  considerable  range  of  coal  and  boilers,  it  would  be  a 
very  laborious  task,  and  a  great  deal  of  valuable  space  would 
be  filled.  It  is  much  more  convenient  to  carry  each  case  by 
itself  from  the  factors  actually  obtained  in  work  daily  accom- 
plished; but  to  show  how  rapidly  and  completely  the  changes 
would  take  place  in  coal  duty  under  various  conditions  of  opera- 
tion, the  accompanying  table  is  given  in  which  the  steam  pres- 
sure is  taken  at  150  Ibs.  per  gauge,  the  temperature  of  feed  is 
taken  at  three  different  points,  the  quality  of  coal  as  to  heat 
units  is  taken  at  four  points,  and  the  efficiency  of  the  boilers  is 
taken  at  16  different  percentages. 

With  the  same  duty  per  1,000  Ibs.  of  steam  given  by  the  engine, 
140,000,000  as  above,  there  is  a  range  in  coal  duty,  or  duty  of 
the  plant,  from  105,000,000  to  152,600,000  per  100  Ibs.  of  coal, 
which  is  the  basis  generally  reported  by  the  water  works 
superintendent,  and  this  basis  seems  to  be  the  most  rational 
one  because  it  deals  directly  with  the  fuel  which  is  bought  and 
the  water  which  is  sold.  Besides  this  the  coal-weighing  is  a 
natural  and  convenient  operation  when  the  fuel  is  brought  into 
the  fire  room  for  use  at  the  boilers,  giving  a  check  against  the 
weights  billed  by  the  dealer  as  time  goes  on;  and  the  different 


f 

COAL  DUTY  OF  PUMPING  ENGINES 


83 


gauges  and  appliances  which  go  with  pumping  engines  afford  an 
easy  way  of  keeping  account  of  the  work  done  by  the  machinery. 
The  following  table  shows  some  of  the  changes  which  take  place 
in  coal  duty  according  to  the  fuel  and  boilers  used : 

Table  showing  what  percentages  of  the  duty  per  1,000  pounds  of  steam 
it  is  possible  to  obtain  with  different  grades  of  coal,  with  different  temper- 
atures of  feed,  and  with  different  efficiencies  of  the  furnaces  and  boilers. 

150  pounds  steam  pressure  per  gauge. 


HEAT  UNITS 

HEAT  UNITS 

HEAT  UNITS 

HEAT  UNITS 

FEU  POUND  OF 

PER  POUND  OF 

PER  POUND  OF 

PER  POUND  OF 

COAL  13,000. 

COAL  13,500. 

COAL  14,000. 

COAL  14,500. 

HEAT 
EFFICIENCY 

OF    THK 
FURNACES 
AND 

Percentages  of 
the  Duty 
per  1,000 
Lbs.  of  Steam 

Percentages  of 
the  Duty 
per  1,000 
Lbs.  of  Steam 

Percentages  of 
the  Duty 
per  1,000 
Lbs.  of  Steam 

Percentages  of 
the  Duty 
per  1,000 
Lbs.  of  Steam 

BOILERS 

at  Given 

at  Given 

at  Given 

at  Given 

GIVEN  IN 

PER    CENT. 

Temperature 
of  Feed. 

Temperature 
of  Feed. 

Temperature 
of  Feed. 

Temperature 
of  Feed. 

100° 

150C 

175° 

:ooc 

150C 

175C 

100C 

150° 

175C 

100° 

150C 

175° 

65 

75 

79 

80 

78 

82 

84 

81 

85 

87 

84 

88 

90 

66 

76 

80 

82 

79 

83 

85 

82 

86 

88 

85 

89 

91 

67 

77 

81 

83 

80 

85 

86 

83 

87 

89 

86 

91 

93 

68 

78 

82 

84 

82 

86 

88 

85 

89 

91 

87 

92 

94 

69 

79 

83 

85 

83 

87 

89 

86 

90 

92 

88 

93 

05 

70 

80 

85 

86 

84 

88 

90 

87 

91 

93 

00 

94 

06 

71 

82 

86 

88 

85 

90 

91 

88 

92 

95 

91 

96 

08 

72 

83 

87 

89 

86 

91 

93 

90 

94 

96 

93 

07 

00 

73 

84 

88 

90 

88 

92 

94 

91 

95 

08 

94 

99 

1C1 

74 

85 

CJ 

C2 

89 

93 

95 

92 

96 

90 

95 

100 

102 

75 

87 

00 

03 

90 

95 

96 

93 

98 

100 

96 

101 

103 

76 

88 

C2 

94 

91 

06 

98 

95 

99 

101 

98 

103 

105 

77 

89 

93 

95 

92 

97 

99 

96 

100 

102 

99 

104 

106 

78 

90 

94 

97 

93 

98 

100 

97 

101 

103 

100 

105 

107 

79 

91 

96 

98 

95 

100 

101 

99 

102 

105 

101 

106 

108 

80 

92 

97 

99 

96 

101 

103 

100 

104 

106 

102 

107 

109 

This  table  is  calculated  by  taking  a  range  of  boiler  efficiencies 
from  65%  to  80%,  as  these  percentages  cover  ordinary,  fair,  good, 
and  excellent  boiler  performance.  There  are  percentages  below 
65,  but  when  there  are,  it  indicates  as  a  general  thing  that  some- 
thing is  seriously  wrong  with  the  boiler  plant  and  needs  looking 
after.  There  are  percentages  above  80,  but  such  a  condition  x)f 


84  PUMPING  ENGINES 

affairs  indicates  that  an  unusually  high  priced  boiler  plant  is  in 
use,  or  unusually  high  priced  fuel  is  being  burned;  both  of  which 
ought  to  be  properly  located  and  adapted,  or  they  will  not  pay 
to  operate. 

These  percentages  of  c  fficiency,  found  in  the  first  column  at  the 
left  hand  side  of  the  table,  represent  the  percentage  in  different 
cases  in  good  practice  of  the  total  heat  of  combustion  possible  to 
obtain  from  the  coal,  which  is  realized  and  used  by  the  furnace 
and  the  boiler  heating  surfaces  in  producing  the  steam.  The 
temperature  of  the  feed  water  going  into  the  boiler,  and  the 
number  of  heat  units,  known  as  British  thermal  units,  contained 
in  one  pound  weight  of  the  water  to  produce  the  temperature 
given  in  the  table,  is  the  starting  point  at  which  the  heat  from 
the  coal  begins  to  operate.  And  the  number  of  heat  units 
necessary  to  produce  one  pound  weight  of  steam  at  the  pressure 
given  at  the  top  of  the  table,  150  Ibs.  per  gauge,  is  the  finishing 
point  reached  by  the  heat  from  the  coal  in  producing  the  steam 
which  comes  out  of  the  boiler. 

The  difference  between  the  number  of  heat  units  in  the  feed 
water  going  into  the  boiler,  and  the  number  of  heat  units  con- 
tained in  the  steam  going  out  of  the  boiler,  shows  how  much 
heat  must  be  furnished  by  the  burning  coal  to  make  the  steam  ; 
and  this  is  reduced  for  convenience  in  making  the  table  to  a  unit 
of  one  pound  in  weight. 

The  temperature  of  the  feed  water  given  in  the  table  at  three 
different  points,  viz:  100°,  150°,  and  175°,  are  probably  as  good  as 
will  be  generally  found  in  practice,  but  the  operations  which 
establish  the  table  may  be  applied  to  any  other  temperatures 
desired.  It  is  obvious  that  the  higher  the  temperature  of  the 
feed,  the  less  will  be  the  number  of  heat  units  required  per  pound 
of  steam  from  the  fuel;  and  the  scale  of  operation  of  these  three 
different  temperatures  appears  as  follows: 
One  pound  of  the  feed  water  - 

At  100°  temperature,  contains  68.08  heat  units  above  32°. 
At  150°  temperature,  contains  118.31  heat  units  above  32°. 
At  175°  temperature,  contains  143.50  heat  units  above  32°. 


f 
COAL  DUTY  OF  PUMPING  ENGINES  85 

One  pound  weight  of  the  steam,  gauge  pressure  150  Ibs.,  con- 
tains 1,193.4  heat  units  above  32°. 

Then  the  difference  in  heat  units  required  to  make  one  pound 
weight  of  steam  from  the  feed  water  at  the  temperatures  given 
in  the  table,  into  steam  at  150  Ibs.  gauge  pressure,  would  be, 

With  feed  at  100°  —  1,125.32  heat  units  per  pound. 
With  feed  at  150°  —  1,075.09  heat  units  per  pound. 
With  feed  at  175°  —  1,049.90  heat  units  per  pound. 

Having  determined  how  much  heat  will  be  necessary  to  make 
one  pound  weight  of  steam  at  150  Ibs.  gauge  pressure,  with 
different  temperatures  of  feed,  the  next  step  is  to  determine 
how  much  heat  may  be  derived  from  the  combustion  of  the  coaL 
And  for  convenience  in  making  a  practicable  table,  four  heat 
values  of  coal  are  taken,  although  the  operations  forming  the 
table  can  be  applied  to  any  heat  value  of  coal.  The  heat  values 
taken  are  at,  13,000  heat  units  per  pound  of  coal;  at  13,500  heat 
units  per  pound;  at  14,000  heat  units  per  pound;  at  14r500  heat 
units  per  pound;  which  is  to  say,  that  in  the  table,  four  grades  of 
coal  are  considered  which  upon  complete  combustion  will  develop 
the  number  of  British  thermal  units  per  pound  set  forth  in  the 
table  in  each  case.  It  being  understood,  as  already  pointed  out,, 
that  the  determined,  or  theoretical  power  of  the  coal  is  very 
much  above  the  possible  results  to  be  found  in  actual  operation 
with  furnaces  and  boilers,  on  account  of  the  various  losses,  such 
as  imperfect  combustion,  more  or  less,  of  the  gases  given  off  by 
the  burning  fuel ;  the  actual  loss  of  some  of  the  coal  by  its  being, 
unburned  and  therefore  remaining  among  the  ashes  and  refuse 
from  the  furnace ;  there  are  also  losses  from  imperfect  transmis- 
sion of  heat  through  the  material  of  the  heating  surfaces  of  the 
boiler  to  the  contained  water,  even  where  the  combustion,  and 
the  production  of  heat,  are  nearly  perfect.  And  it  is  the  general 
result  found  in  practice  which  marks  the  difference  between  the 
real  amount  of  heat  of  perfect  combustion  and  the  amount  of 
heat  actually  present  in  the  steam  produced,  which  go  to  make 
up  the  column  of  percentages  at  the  left  hand  side  of  the  table, 


86  PUMPING  ENGINES 

showing  the  practical  efficiency  of  the  boiler  and  furnace  as  a 
steam-making  apparatus,  in  proportion  to  the  heat  value  of  the 
coal  burned  upon  the  grates.  Any  boiler  efficiency  known  or 
selected  from  the  table  in  per  cent  in  the  left  hand  column,  will 
apply  to  any  of  the  heat  values  of  the  coal  given,  or  any  other 
heat  value  will  show  how  many  heat  units  per  pound  of  coal 
the  boiler  is  having  the  use  of  in  producing  steam.  Then  this 
net  number  of  heat  units  derived  from  a  pound  of  coal  by  the 
boiler,  divided  by  the  range  of  heat  units  between  the  feed  and 
the  steam  pressure,  will  indicate  the  actual  evaporation  of  pounds 
of  water  per  pound  of  coal  under  the  working  conditions;  and 
the  decimal  point  in  the  rate  of  evaporation  so  found,  if  moved 
one  place  to  the  left  will  express  the  percentage  of  the  duty 
per  1,000  Ibs.  of  steam  which  will  be  obtained  per  100  Ibs.  of 
coal. 

If  the  decimal  point  be  placed  between  the  two  figures  where 
there  are  two  figures  only,  or  at  the  left  side  of  the  right  hand 
figure  where  there  are  three  figures,  found  in  this  table  expressing 
percentages  of  duty  in  the  columns  under  temperatures  of  feed, 
the  result  will  show  the  evaporation  per  pound  of  coal  going  on 
in  the  boiler,  with  the  heat  value  of  the  coal  and  the  efficiency 
of  boiler  given  above,  and  opposite,  the  percentage  of  duty 
selected. 

Where  the  percentage  of  the  duty  per  1,000  Ibs.  of  steam 
reaches  in  the  table  to  100  or  above,  and  which  it  does  in  a  num- 
ber of  places,  this  indicates  that  the  actual  evaporation  in  the 
boiler,  either  from  high  efficiency  of  boiler  or  from  high  heat 
value  of  the  coal,  or  both,  is  more  than  10  to  1,  the  commonly 
accepted  basis  for  making  comparisons  in  duty  tests  of  pumping 
engines. 

Aside  from  the  heat  value  of  the  coal  burned  in  a  water  works 
plant,  there  is  also  a  money  value.  And  the  question  is  often 
brought  up  in  considering  the  practical  value  of  economic  duty, 
especially  where  it  involves  a  comparatively  high  cost  of  ma- 
chinery, as  to  what  price  per  ton  as  coal  is  commercially  bought, 
it  will  pay  to  go  in  purchasing  supplies.  Of  course  the  better 


COAL  DUTY  OF  PUMPING  ENGINES 


87 


the  quality  the  more  it  is  worth,  but  there  is  a  dividing  line,  where 
the  heat  units  possible  to  obtain  from  the  combustion  balances 
against  the  price  in  money  which  must  be  paid  for  any  particular 
grade  of  fuel.  And  as  heat  units  are  eventually  obtained  for 
the  money  paid  out,  a  comparison  between  these  two  items  will 
be  in  order;  but  the  question  is  too  complex  to  go  into  extensively 
within  the  limits  of  this  book,  although  a  meager  outline  will  be 
given  to  indicate  the  direction  possible  to  follow  where  the 
necessary  information  is  available. 

BITUMINOUS  COAL 

With  a  bituminous  coal  showing  say  14,500  heat  units  per 
pound  and  costing  say  $3  per  net  ton  of  2,000  pounds,  the 
buyer  will  receive  96,666  heat  units  for  a  cent.  And  taking 
this  as  a  basis  of  value  for  other  coals,  the  following  table  of 
price  or  money  value  for  different  grades  of  coal  in  proportion 
to  the  ability  to  furnish  heat  appears: 


HEAT  UNITS  PER 
POUND  ON  COMPLETE 
COMBUSTION. 

PRICE  PER  NET  TON 
OF  2,000  POUNDS 
DELIVERED  IN  THE 
BOILER  ROOM. 

14,500 

$3.00 

14,250 

2.94 

14,000 

2.89 

13,750 

2.84 

13,500 

2.79 

13,250 

2.74 

13,000 

2.68 

12,750 

2.63 

12,500 

2.58 

12,250 

2.53 

12,000 

2.48 

These  results  are  obtained  by  multiplying  the  heat  units  from 
one  pound  of  the  coal  at  the  price  of  $3  per  ton,  which  is  14,500 
and  is  taken  as  a  standard,  by  2,000,  the  number  of  pounds  in  a 
net  ton;  and  this  result  divided  by  300  cents  ($3)  gives  the  num- 
ber of  heat  units  for  one  cent  based  upon  a  fair  market  price  for  a 


88  PUMPING  ENGINES 

good  quality  of  soft  coal,  and  amounts  to  96,666  heat  units  for 
a  cent.  Then  the  heat  units  for  a  cent,  in  this  particular  case 
95,666,  divided  into  the  heat  units  in  one  ton,  which,  2,000,  multi- 
plied by  the  number  of  heat  units  per  pound  of  the  coal,  will 
give  the  price  value  of  the  coal  in  cents,  which  pointed  off  in 
two  places  will  give  dollars  and  cents  per  ton,  upon  the  basis 
of  $3  for  the  higher  quality.  If  the  price  of  the  higher  quality 
varies  in  different  markets  or  places  then  the  comparative  price 
for  the  other  grades  will  also  vary,  but  the  proportion  of  price 
to  heat  units  will  hold  good  whatever  the  basic  price  or  the  loca- 
tion of  the  market  where  the  coal  is  bought. 

The  results  would  be  modified  to  a  slight  extent  by  the 
difference  hi  coal  arising  from  other  elements  than  the  mere 
difference  in  total  heat  units;  as,  for  example,  fixed  carbon  in 
the  coal,  which  is  the  most  valuable  portion  of  the  fuel  from  a 
practical  standpoint  because  it  is  the  easiest  to  accommodate  to 
the  combustion  within  the  furnace;  whereas  the  gaseous  portion 
of  the  coal  although  equally  valuable  under  proper  conditions 
is  more  difficult  to  manage  economically.  In  soft  coal  the  fixed 
carbon  or  solid  portion  of  the  fuel  varies  from  54%  to  83%  while 
the  gaseous  or  volatile  matter  varies  from  12%  to  48%,  and 
hence  the  same  arrangement  for  furnace,  air,  and  draught  will 
not  answer  for  all  grades  of  coal.  But  with  fixed  carbon  varying 
from  68%  to  78%  and  a  low  amount  of  sulphur,  very  good  results 
will  be  found  according  to  the  table,  and  based  upon  the  total 
amount  of  heat  units  per  pound.  It  is  not  difficult  to  ascertain 
the  difference  in  quality  of  coals,  and  it  will  no  doubt  pay  to  give 
some  attention  to  the  subject  when  making  contracts  for  supplies 
of  fuel  for  water  works  purposes. 

ANTHRACITE  COAL 

With  an  anthracite  coal  showing  say  14,000  heat  units  per 
pound  on  total  combustion,  and  costing  say  $4.50  per  net  ton  of 
2,000  pounds,  the  buyer  will  receive  62,222  heat  units  for  a  cent. 
And  taking  this  as  a  basis  of  value  for  other  grades,  the  following 


COAL  DUTY  OF  PUMPING  ENGINES 


89 


table  of  price  or  money  value  for  different  grades  of  coal  in  pro- 
portion to  the  ability  to  furnish  heat  appears : 


HEAT  UNITS  PER 
POUND  ON  COMPLETE 
COMBUSTION. 

PRICE  PER  NET  TON 
OF  2,000  POUNDS 
DELIVERED  IN  THE 
BOILER  ROOM. 

14,000 

$4.50 

13,750 

4.42 

13,500 

4.36 

13,250 

4.26 

13,000 

4.17 

12,750 

4.10 

12,500 

4.02 

12,250 

3.94 

12,000 

3.86 

This  table  is  constructed  by  the  same  method  as  the  bitumi- 
nous table  immediately  preceding,  .and  subject  to  the  same 
restrictions  regarding  elements  in  the  coal,  but  the  difference 
against  the  anthracite  in  price  is  not  quite  so  great  as  apparent 
at  first  glance,  for  the  reason  that  the  fixed  carbon  is  about  20% 
higher  in  anthracite  than  in  bituminous  on  the  average,  so  where 
freight  rates,  losses  from  storage  and  from  weather,  and  other 
factors  play  a  part,  sometimes  the  higher  priced  anthracite  is 
the  most  economical  in  proportion  to  water  pumped.  As  an 
example  of  this  two  records  are  given  in  actual  practice  based 
upon  the  generally  accepted  factor  of  coal  consumed  per  indi- 
cated horse  power  per  hour,  and  which  were  as  follows: 

In  one  case  there  was  consumed  1.02  pounds  of  coal  per  indi- 
cated horse  power,  and  in  the  other  case  1.98  pounds  of  coal 
per  indicated  horse  power  per  hour.  Both  records  were  ob- 
tained as  nearly  as  could  be  under  similar  conditions  in  actual 
water  works  pumping.  The  fuel  calling  for  1.98  pounds  was 
anthracite  slack;  and  the  fuel  calling  for  1.02  pounds  was  a  good 
quality  of  anthracite  coal.  The  slack  was  $1.50  per  net  ton,  and 
the  regular  coal  was  $4.50  per  net  ton.  The  analysis  of  the 
fuels  for  heat  units  on  complete  combustion  was  as  follows: 

Heat  units  for  the  slack,  11,000  per  pound. 

Heat  units  for  the  coal,  14,000  per  pound. 

(These  are  closely  approximate  round  numbers.) 


90  PUMPING  ENGINES 

In  the  case  of  the  slack  the  buyer  obtained  146,000  heat  units 
for  a  cent;  and  in  the  case  of  the  coal  the  buyer  obtained  62,000 
heat  units  for  a  cent. 

The  plant  using  the  slack  consumed  363  heat  units  per  horse 
power  per  minute  on  the  coal  duty  basis,  and  the  plant  using  the 
regular  anthracite  coal  consumed  238  heat  units  per  horse  power 
per  minute  upon  the  coal  duty  basis.  The  efficiency  of  the 
boilers  was  70%  in  the  case  of  the  slack,  and  80%  efficiency  in 
the  case  of  the  coal.  This  gives  8,579,970  ft.  Ibs.  of  work  for 
a  cent  with  the  slack,  and  13,200,000  ft.  Ibs.  of  work  for  a  cent 
with  the  regular  coal. 

The  horse  power  was  about  the  same,  and  has  been  equalized 
in  the  calculation  at  625  indicated  horse  power,  which  makes 
the  slack  cost  95  cents  per  hour  for  the  power  required,  and  the 
coal  cost  $1.63  per  hour  for  the  same  power.  But  the  slack  is 
used  practically  at  the  point  of  production  while  the  coal  is 
freighted  several  hundred  miles,  and  if  the  price  of  the  slack 
should  be  raised  $1.25  per  ton,  making  it  cost  $2.75  per  ton, 
then  the  cost  of  the  power  would  be  $1.70  per  hour  as  against 
$1.63  per  hour  for  the  coal. 

Or  to  put  it  another  way,  it  will  require  27%  more  of  the  slack 
to  obtain  the  same  number  of  heat  units  that  a  pound  of  the 
coal  is  good  for,  and  even  at  $1.50  per  ton,  the  increase  in  the 
quantity  would  carry  the  price  of  the  slack  up  to  an  equivalent 
of  $1.90  per  ton,  and  the  increased  quantity  would  allow  a 
freight  rate  of  only  65  cents  per  ton,  to  keep  the  cost  for  the 
power  per  hour  down  to  $1.70  or  7  cents  above  the  cost  of  the 
coal  upon  the  same  basis.  It  is  extremely  doubtful  if  the  slack 
can  be  freighted  the  distance  required  for  65  cents  per  ton, 
and  aside  from  this  there  would  be  an  increased  quantity  of 
ashes  to  be  taken  care  of  and  to  dispose  of  in  the  operation  of 
the  plant. 

It  is  sometimes  convenient  to  know  at  a  glance  what  the  duty 
will  be  for  any  certain  rate  of  actual  evaporation  in  the  boilers, 
under  every-day  working  conditions  usually  found  in  the  boiler 
room  of  a  pumping  plant.  In  large  engines  and  under  good 


COAL  DUTY  OF  PUMPING  ENGINES 


91 


boiler  conditions,  yearly  duties  are  maintained  as  high  as  from 
120,000,000  to  135,000,000  ft.  Ibs.  per  100  Ibs.  of  coal  burned; 
and  it  must  be  borne  in  mind  that  no  matter  how  high  a 
steam  duty  a  pumping  engine  may  show,  the  results  at  the 
boilers  in  producing  the  steam  have  a  strong  controlling  influence 
upon  the  yearly  reports  of  economical  operation.  To  illustrate 
the  difference  that  can  exist  between  steam  duty  per  1,000  Ibs. 
and  coal  duty  per  100  Ibs.  based  upon  the  actual  weight  of  fuel 
required,  the  accompanying  table  is  given. 


Duty  on  coal  burned  in  the  furnaces  of  the  boilers,  for  different  rates  of 
evaporation,  and  for  the  following  duties  per  1,000  pounds  of  steam. 


DUTY  IN  FOOT 
POUNDS  PER 
1,000  POUNDS  OF 
DRY  STEAM. 

DUTY  IN  FOOT  POUNDS  FER  100  POUNDS  OF  COAL  FOR 
DIFFERENT  KATES  OF  ACTUAL  EVAPORATION  IN  THE  BOILERS. 

8  Pounds. 

8.5  Pounds. 

9  Pounds. 

9.5  Pounds. 

40,000,000 

32,000,000 

34,000,000 

36,000,000 

38,000,000 

50,000,000 

40,000,000 

42,500,000 

45,000,000 

47,500,000 

60,000,000 

48,000,000 

51,000,000 

54,000,000 

57,000,000 

70,000,000 

56,000,000 

59,500,000 

63,000,000 

66,500,000 

80,000,000 

64,000,000 

68,000,000 

72,000,000 

76,000,000 

90,000,000 

72,000,000 

76,500,000 

81,000,000 

85,500,000 

100,000,000 

80,000,000 

85,000,000 

90,000,000 

95,000,000 

110,000,000 

88,000,000 

93,500,000 

99,000,000 

104,500,000 

115,000,000 

92,000,000 

97,750,000 

103,500,000 

109,250,000 

120,000,000 

96,000,000 

102,000,000 

108,000,000 

114,000,000 

125,000,000 

100,000,000 

106,250,000 

112,500,000 

118,750,000 

130,000,000 

104,000,000 

110,500,000 

117,000,000 

123,500,000 

135,000,000 

108,000,000 

114,750,000 

121,500,000 

128,250,000 

140,000,000 

112,000,000 

119,000,000 

126,000,000 

133,000,000 

145,000,000 

116,000,000 

123,250,000 

130,500,000 

137,750,000 

150,000,000 

120,000,000 

127,500,000 

135,000,000 

141,500,000 

155,000,000 

124,000,000 

132,750,000 

139,500,000 

147,250,000 

160,000,000 

128,000,000 

136,000,000 

144,000,000 

152,000,000 

165,000,000 

132,000,000 

140,250,000 

148,500,000 

156,750,000 

170,000,000 

136,000,000 

144,500,000 

153,000,000 

161,500,000 

175,000,000 

140000,000 

148,750,000 

157,500,000 

166,250,000 

180,000,000 

144,000,000 

153,000,000 

162,000,000 

171,000,000 

185,000,000 

148,000,000 

157,250,000 

166,500,000 

175,750,000 

190,000,000 

152,000,000 

161,500,000 

171,000,000 

180,500,000 

195,000,000 

156,000,000 

165,750,000 

175,000,000 

185,250,000 

200,000,000 

160,000,000 

170,000,000 

180,000,000 

190,000,000 

CHAPTER   VIII 
ACTUAL  CONDITIONS   OF   PUMPING 

WITH  a  properly  designed  and  well  built  machine,  its  actual 
steam  economy  should  be  maintained  at  very  nearly  the  maxi- 
mum, and  no  doubt  it  is  in  a  great  majority  of  cases;  in  fact, 
unless  cutting  or  other  damage  to  valves  and  pistons  takes  place, 
the  initial  efficiency  cannot  be  lowered  very  much  without 
gross  inattention,  or  without  a  very  serious  departure  from  the 
steam  and  water  pressures  for  which  the  engine  was  built.  But 
where,  as  in  the  usual  annual  report  of  the  water  works  superin- 
tendent, the  statement  of  duty  is  in  terms  of  coal,  it  will  be  seen 
at  once  that  there  are  a  good  many  chances  for  losses  of  various 
kinds.  When  operated  under  good  conditions  there  is  not  very 
much  difference  in  boilers  so  far  as  efficiency  is  concerned,  but 
when  boilers  are  worked  under  bad  conditions  there  is  a  different 
story  to  tell.  There  are  three  prominent  items  affecting  the 
actual  coal  duty  of  a  pumping  plant  pertaining  to  the  boilers. 
They  are,  overworked  boilers;  underworked  boilers;  and  vari- 
ous kinds  of  coal.  And  for  any  shortcomings  in  any  of  these 
or  other  directions  belonging  to  the  boilers,  the  engine  is  not 
responsible. 

Another  reason  why  pumping  engines  sometimes  fall  short 
in  duty  in  regular  service  is  that  they  are  not  always  properly 
proportioned  to  the  work  to  be  done.  This  cannot  be  helped 
sometimes.  The  future  must  sometimes  be  reckoned  for,  and 
when  an  engine  is  put  in,  it  must  sometimes  be  larger  than 
present  needs  demand.  But  the  contractor  is  entitled  to  test 
his  engine  under  the  best  conditions  for  which  it  is  built,  and 
therefore  when  the  experts  get  away  and  the  machine  is  put 
into  the  regular  service  the  ideal  conditions  are  destroyed  and 

92 


I 

ACTUAL  CONDITIONS  OF  PUMPING  93 

unfavorable  conditions  substituted.  Chicago,  for  example, 
had  such  an  experience  some  years  ago.  The  engines  adver- 
tised for  were  proportioned,  according  to  the  specifications,  to 
pump  against  a  head  50%  greater  than  really  developed  in 
regular  service,  with  the  result  that  triple  expansion  engines 
were  placed  under  conditions  where  compound  engines  with 
smaller  steam  ends  would  have  undoubtedly  done  much 
better  economic  work.  What  happened,  apparently,  was  that 
the  high  and  intermediate  pressure  cylinders  did  so  much  of 
the  work  that  there  was  only  a  low  temperature  fog  left  for  the 
low  pressure  cylinder  to  handle,  and  the  third  plunger  was 
largely  operated  through  the  medium  of  the  crank  and  connect- 
ing rod,  dragging  the  low  pressure  piston  along  incidentally.  No 
comments  are  offered  upon  the  facts;  the  reference  is  only  used 
as  an  illustration  of  how  disappointment  may  be  met  with, 
even  though  a  high  type  of  machine  is  secured.  It  further 
illustrates  how  a  duty  test  run  by  experts  under  proper  condi- 
tions may  be  greatly  discounted  in  every-day  operation,  and 
where  "somebody  blundered,"  but  where  the  engines  and  the 
experts  were  not  to  blame  for  the  shortcomings. 

Reference  has  just  been  made  to  overworked  and  underworked 
boilers;  and  this  suggests  an  appropriate  illustration  upon  this 
point  as  to  how  much  the  required  amount  of  heating  surface 
in  boilers  will  vary  to  suit  different  rates  of  economy  in  the 
steam  consumption  of  the  pumping  machinery,  covering  the 
different  types  and  classes  of  pumping  engines  as  follows : 

Compound  non-condensing,  direct  acting. 
Compound  condensing,  direct  acting. 
Low  duty  triple  expansion,  direct  acting. 
High  duty  compound  condensing,  direct  acting. 
High  duty  triple  expansion  condensing,  direct  acting. 
Cross-compound  condensing,  crank  and  fly  wheel. 
Double  compound  condensing,  crank  and  fly  wheel. 
Triple  expansion  condensing,  crank  and  fly  wheel. 
Quadruple  expansion  condensing,  crank  and  fly  wheel. 


9t  PUMPING  ENGINES 

The  relation  between  the  difference  in  economical  duty  of 
the  various  types  and  classes  of  pumping  engines,  and  the 
amount  of  boiler  required,  may  be  conveniently  shown  by  the 
accompanying  table;  the  measurable  amount  of  boiler  needed 
being  positively  indicated  by  taking  10  square  feet  of  heating 
surface  as  ordinarily  measured  for  each  boiler  horse  power. 
The  table  is  based  upon  the  fact  repeatedly  demonstrated  by 
easily  evaporating  a  little  over  10,500  Ibs.  of  water  per  hour 
in  a  pair  of  water  tube  boilers  having  3,500  square  feet  of  heat- 
ing surface,  that  in  good  ordinary  practice,  one  square  foot 
of  heating  surface  will  evaporate  3  Ibs.  of  water  per  hour, 
from  150°  temperature  of  feed  into  steam  at  150  Ibs.  gauge 
pressure.  And  therefore  10  square  feet  will  evaporate  30  Ibs. 
of  water  per  hour  as  above,  and  this  amount  of  evaporation 
is  taken  as  one  boiler  horse  power.  This  at  least  is  a  good 
basis,  safe  in  most  cases;  but  if  at  any  time  caution,  or  any 
special  reasons,  should  suggest  an  increase  in  heating  surface, 
any  certain  desired  percentage  increase  can  be  readily  added 
without  disturbing  the  relations  of  the  different  rates  of  economy; 
as,  for  example,  if  it  should  be  decided  that  2J  Ibs.  of  water  per 
square  foot  of  heating  surface  per  hour  is  all  that  it  would  be 
safe  to  reckon  upon,  then  20%  added  to  the  boiler  horse  power 
of  the  table  would  provide  for  such  a  case.  Or,  if,  to  go  to 
extremes  somewhat,  it  was  thought  that  2  Ibs.  of  water  per 
hour  per  square  foot  of  heating  surface  was  the  limit,  then  50% 
added  to  the  table  would  meet  the  demands  for  boiler  capa- 
city. But  the  writer  believes  that  with  properly  constructed 
and  arranged  boilers,  the  table  will  answer  all  reasonable 
purposes. 

The  economy  of  the  pumping  engines,  which  is  entirely  inde- 
pendent of  the  working  of  the  boilers,  is  expressed  in  foot 
pounds  duty  per  1,000  Ibs.  of  steam,  in  the  left  hand  column  of 
the  table. 

The  second  column  of  the  table  is  calculated  by  ascertaining 
the  steam  per  pump  horse  power  per  hour  by  dividing  the  duty 
given  in  the  table  by  1,000,  which  gives  the  duty  per  pound  of 


I 

ACTUAL  CONDITIONS  OF  PUMPING 


95 


steam  consumed;  and  then  dividing  the  foot  pounds  of  work 
of  one  horse  power  per  hour,  equal  to  60  times  33,000  or  1,980,000 
foot  pounds,  by  the  duty  per  pound  of  steam  consumed  already 
ascertained.  The  result  will  be  the  steam  per  pump  horse 
power  per  hour  at  the  rate  of  duty  selected  from  the  table,  or 
any  other  duty  may  be  treated  in  the  same  manner. 

Then  the  steam  per  pump  horse  power  per  hour  divided  by 
30,  which  is  the  steam  per  boiler  horse  power  per  hour,  will  give 
the  required  boiler  horse  power,  per  pump  horse  power  of  the 
pumping  engine. 

Boiler  Horse  Power  required  for  each  Pump  Horse  Power;  counting 

10  square  feet  of  Heating  Surface  for  each  Boiler  Horse  Power, 

for  the  following  Duties  of  Engines. 


DUTY  IK  FOOT  POUNDS  PER 
1,000  POUNDS  OF  STEAM. 

POUNDS  OF  STEAM 
PER  HOUK  PER  PUMP 
HOKSE  POWER. 

BOILER  HORSE  POWER 
PER  PUMP  HORSE 
POWER. 

40,000,000 

49.50 

1.63 

50,000,000 

39.60 

1.32 

60,000,000 

33.00 

1.10 

70,000,000 

28.38 

0.94 

80,000,000 

24.75 

0.83 

90,000,000 

22.00 

0.74 

100,000,000 

19.80 

0.66 

110,000,000 

18.00 

0.60 

115,000,000 

17.21 

0.57 

120,000,000 

16.50 

0.55 

125,000,000 

15.80 

0.52 

130.000,000 

15.20 

0.51 

135,000,000 

14.66 

0.49 

140,000,000 

14.14 

0.47 

145,000,000 

13.65 

0.46 

150,000,000 

13.20 

0.44 

155,000,000 

12.77 

0.43 

160,000,000 

12.37 

0.41 

165,000,000 

12.00 

0.40 

170,000,000 

11.65 

0.39 

175,000,000 

11.31 

0.38 

180,000,000 

11.00 

0.37 

185,000,000 

10.70 

0.36 

190,000,000 

10.42 

0.35 

195,000,000 

10.01 

0.34 

200,000,000 

9.90 

0.33 

There  are  two  phases  of  the  question  of  the  power  required 
for  pumping  water  which  are  closely  relative  to  the  foregoing 


96  PUMPING  ENGINES 

table,  and  these  are,  the  pump  horse  power  for  various  quan- 
tities of  water  pumped  against  different  pressures,  and  the 
indicated  steam  power  developed  in  the  steam  cylinders  cor- 
responding to  the  quantities  and  pressures  given  for  the  pump 
end  of  the  machine;  and  at  different  mechanical  efficiencies  of 
the  engine  as  a  whole.  The  powers  given  for  the  water  ends 
of  the  engines  are  the  net  powers  represented  by  the  weight 
of  the  quantity  of  water  per  minute,  multiplied  by  the  total 
head  in  feet  including  suction  and  friction  in  the  water,  as 
shown  by  the  pressure  gauge,  or,  in  other  words,  the  actual 
power  developed  by  the  water  end  of  the  working  engine,  and 
exclusive  of  the  friction  of  the  machine. 

The  table  herewith,  of  water  end  or  pump  horse  power,  is 
based  upon  an  easily  remembered  rule  which  may  be  quite 
readily  committed  to  memory,  and  is  based  upon  the  fact 
that  with  2,500,000  gallons  of  water  per  24  hours  the  actual 
horse  power  of  the  water  column  is  one  horse  power  for  each 
pound  of  water  pressure,  reckoning  the  total  load  and  including 
the  suction  lift.  This  total  load  is  made  up  by  accurately  read- 
ing the  water  pressure  gauge,  and  then  adding  to  the  reading 
in  pounds,  the  distance  from  the  center  of  this  gauge  down 
to  the  level  of  the  water  in  the  pump  well,  this  latter  distance 
converted  into  Ibs.  pressure  by  dividing  the  vertical  distance 
in  feet  by  2.31  feet  per  pound  pressure.  This  will  give  a  result 
within  one  per  cent  of  what  an  accurate  calculation  made  in 
the  usual  way  will  produce;  and  when  it  is  considered  how 
extremely  difficult  it  is  to  establish  absolutely  accurate  /pres- 
sures from  reading  gauges  or  observing  mercury  columns,  with 
all  the  necessary  corrections  for  mercury  at  different  tempera- 
tures, the  eccentricities  of  Bourdon  gauge  springs,  and  other 
chances  for  error  so  well  known  to  the  expert  (the  more  ex- 
pert he  is,  the  more  errors  he  knows  about),  a  margin  of  one 
per  cent,  and  that  against  the  machine,  may  be  considered 
pretty  close.  Then  whatever  multiple  the  quantity  of  water 
to  be  considered,  is  of  2,500,000,  so  will  the  horse  power  figures 
be  determined. 


ACTUAL  CONDITIONS  OF  PUMPING 


97 


Table  Showing  Horse  Power  of  Water  End  of  Pumping  Engines. 


TOTAL  WATER  LOAD  AGAINST  PLUNGERS  IN  POUNDS 

PRESSURE,  INCLUDING  SUCTION. 

CAPACITY 

IN  U.  S. 

GALLONS 

PER  24 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

HOURS. 

Horse  Powers  of  the  Water  Ends. 

1,000,000 

16 

20 

24 

28 

32 

36 

40 

44 

48 

52 

56 

60 

1,500,000 

24 

30 

36 

42 

48 

54 

60 

66 

72 

78 

84 

90 

2,000,000 

32 

40 

48 

56 

64 

72 

80 

88 

96 

104 

112 

120 

2,500,000 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

3,000,000 

48 

60 

72 

84 

96 

108 

120 

132 

144 

156 

168 

180 

4,000,000 

64 

80 

96 

112 

128 

144 

160 

176 

192 

208 

224 

240 

5,000,000 

80 

100 

120 

140 

160 

180 

200 

220 

240 

260 

280 

300 

6,000,000 

96 

120 

144 

168 

192 

216 

240 

264 

288 

312 

336 

360 

7,000,000 

112 

140 

168 

196 

224 

252 

280 

308 

336 

364 

392 

420 

8,000,000 

128 

160 

192 

224 

256 

288 

320 

352 

384 

416 

448 

480 

9,000,OOC 

144 

180 

216 

252 

288 

324 

360 

396 

432 

468 

504 

540 

10,000,OOC 

160 

200 

240 

280 

320 

360 

400 

440 

480 

520 

560 

600 

11,000,00( 

176 

220 

264 

308 

352 

396 

440 

484 

528 

572 

616 

660 

12,000,00( 

192 

240 

288 

336 

384 

432 

480 

528 

576 

624 

672 

720 

13,000,OOC 

208 

260 

312 

364 

416 

468 

520 

572 

624 

670 

728 

780 

14,000,OOC 

224 

280 

336 

392 

448 

504 

560 

616 

672 

728 

784 

840 

15,000,OOC 

240 

300 

360 

420 

480 

540 

600 

660 

720 

780 

840 

COO 

16,000,000 

256 

320 

384 

448 

512 

576 

640 

704 

768 

832 

896 

960 

17,000,000 

272 

340 

408 

476 

544 

612 

680 

748 

816 

884 

952 

1020 

18,000,000 

288 

360 

432 

504 

576 

648 

720 

792 

864 

936 

1008 

1080 

20,000,000 

320 

400 

480 

560 

640 

720 

800 

880 

960 

1040 

1120 

1200 

22,000,000 

352 

440 

528 

616 

704 

792 

880 

968 

1056 

1144 

1232 

1320 

25,000,000 

400 

500 

600 

700 

800 

900 

1000 

1100 

1200 

1300 

1400 

1500 

30,000,000 

480 

600 

720 

840 

960 

1080 

1200 

1320 

1440 

1560 

1680 

1800 

35,000,000 

560 

700 

840 

980 

1120 

1260 

1400 

1540 

1680 

1820 

1960 

2100 

40,000,000 

640 

800 

960 

1120 

1280 

1440 

1600 

1760 

1920 

2080 

2240 

2400 

As  an  example  from  the  foregoing  table,  5,000,000  is  twice 
2,500,000,  and  so  the  horse  power  for  the  5,000,000  will  be  double 
the  water  load  in  pounds;  and  for  10,000,000  gallons  will  be  4 
times  the  water  load  in  pounds.  This  means  that  the  quantity 
of  water  in  U.  S.  gallons  per  24  hours  for  which  the  horse 
power  is  wanted,  is  to  be  divided  by  2,500,000  and  the  result 
multiplied  by  the  water  load  in  pounds  pressure,  the  product 
giving  the  horse  power  of  the  water  column.  After  a  little 
practice  this  rule  may  be  readily  used  mentally,  and  the  power 
determined  with  great  quickness  and  accuracy. 


98  PUMPING  ENGINES 

If  it  is  desired  in  using  this  table,  to  ascertain  the  horse  power 
for  any  quantity  of  water  given  in  the  left  hand  column  of 
the  table  but  for  a  water  pressure  load  not  given  in  the  table, 
then  find  the  horse  power  opposite  the  quantity  of  water  con- 
sidered, and  under  100  Ibs.  pressure;  point  off  two  places  of 
decimals  from  the  right  and  multiply  by  the  pressure  given 
or  desired;  the  result  will  be  the  horse  power. 

The  power  of  the  steam  end  of  the  pumping  engine,  called 
the  Indicated  Horse  Power,  is  one  of  the  important  guides  in 
considering  the  economical  efficiency  of  the  machine;  and  the 
pounds  of  steam  per  indicated  horse  power  per  hour  as  showing 
the  power  produced  in  proportion  to  the  steam  supplied  to 
the  engine  is  closely  observed.  The  relation  between  the 
indicated  horse  power  and  the  pump  or  water  end  horse 
power,  discloses  the  mechanical  efficiency  of  the  machine,  or, 
in  other  words,  shows  how  much  of  the  power  produced  in  the 
engine  by  the  heat  energy  is  utilized  as  useful  work.  This 
difference  between  what  is  shown  to  exist  as  power  in  the 
steam  cylinders,  and  what  is  shown  to  exist  as  useful  work 
in  the  pump  cylinders,  is  lost  in  friction  either  of  the  working 
parts  of  the  machine  itself,  or  of  the  water  passing  through 
the  pumps,  or  both.  And  many  disappointments  have  been 
met  with  after  developing  a  very  nearly  perfect  steam  per- 
formance, by  seeing  the  heat  efficiency  of  the  steam  engine 
so  dearly  bought,  disappear  in  the  doing  of  useless  work  within 
the  machine  itself.  This  mechanical  efficiency  of  pumping 
engines,  of  capacities  ranging  from  6,000,000  U.  S.  gallons  to 
35,000,000  U.  S.  gallons  per  24  hours,  varies  all  the  way  from 
88.6%  to  96.8%  in  machinery  designed  and  built  by  the  best 
and  leading  engineers  and  establishments  in  this  country. 

The  records  plainly  show  the  close  relation  between  the 
mechanical  and  steam  efficiencies,  for  with  the  best  and  the 
largest  engines,  the  low  mechanical  efficiency  and  the  lower 
ranges  of  duty  go  hand  in  hand;  when  the  former  is  in  the 
neighborhood  of  88%  the  latter  is  around  157,000,000  ft.  Ibs., 
and  the  high  duty  record  up  to  April,  1906,  was  held  slightly 


f 

ACTUAL  CONDITIONS  OF  PUMPING  99 

above  179,000,000  ft.  Ibs.  with  a  mechanical  efficiency  of  96.8% 
in  the  machine.  The  size  of  the  machine  does  not  always 
control,  because  the  record  shows  a  6,000,000  gallon  engine 
with  a  mechanical  efficiency  of  93%  and  a  35,000,000  gallon 
engine  with  88%  as  its  efficiency  record.  Nor  does  the  water 
load  or  pressure  altogether  govern  in  the  matter,  for  the  record 
shows  252  Ibs.  water  load  with  93%  and  54  Ibs.  pressure  with 
96.5%  mechanical  efficiency.  The  probabilities  are  that  the 
larger  machine  under  the  same  working  load  will  show  the 
greater  efficiency,  and  the  smaller  machine  under  any  load, 
other  things  being  equal,  will  show  the  lesser  efficiency. 

The  mechanical  efficiency  of  pumping  engines,  or  their  net 
effectiveness  for  doing  useful  work,  shown  in  the  extreme  right 
hand  column  of  the  accompanying  table  of  indicated  horse 
power,  is  the  percentage  which  the  water  end  horse  power  is 
of  the  steam  end  horse  power;  and  may  also  be  expressed  by 
an  ordinary  fraction  in  which  the  water  end  horse  power  is  the 
upper  term  and  the  steam  end  horse  power  is  the  lower  term, 
or,  the  numerator  and  the  denominator;  as,  for  example,  with 
a  10,000,000  gallon  engine  working  against  100  Ibs.  pressure, 
the  water  end  horse  power  is  400  and  the  steam  end  horse  power 
is  450  at  89  per  cent  mechanical  efficiency.  Then  the  ordinary 
fraction  would  be  Jf  $  or  by  placing  a  decimal  point  after  the  400 
and  annexing  ciphers  to  the  numerator,  divide  by  the  denomi- 
nator in  the  usual  way  for  transposing  the  ordinary  fractions 
into  decimal  fractions,  and  the  mechanical  efficiency  is  expressed 
in  per  cent,  in  this  case  resulting  in  89  per  cent. 

The  table  showing  mechanical  efficiency,  indicated  horse 
power,  water  load  against  the  plungers,  and  daily  capacity 
follows: 


100 


PUMPING  ENGINES 


Table  of  Mechanical  Efficiency  of  Pumping  Engines,  Showing  the 
Indicated  Horse  Power  in  the  Steam  Cylinders. 


TOTAL  WATER  LOAD  AGAINST  THE  PLUNGERS  IN  POUNDS 

'*  t£ 

PRESSURE,  INCLUDING  SUCTION. 

*$£ 

CAPACITY 

fc  O 

U.  S. 

H^  PH 

GALLONS 

PER 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

fc'  ® 

24  HOURS. 

•  < 

Indicated  Horse  Power  of  the  Steam  Cylinders. 

ll 

1,000,000 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

70 

75 

80 

1,500,000 

30 

37 

44 

52 

58 

66 

74 

81 

90 

96 

104 

111 

81 

2,000,000 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

82 

2,500,000 

48 

60 

72 

82 

96 

110 

120 

133 

145 

160 

170 

180 

83 

3,000,000 

55 

71 

84 

100 

114 

128 

143 

157 

171 

185 

200 

214 

84 

4,000,000 

75 

94 

113 

132 

150 

170 

188 

207 

226 

245 

264 

283 

85 

5,000,000 

93 

116 

140 

161 

186 

210 

234 

255 

280 

304 

325 

350 

86 

6,000,000 

110 

138 

166 

205 

220 

248 

276 

303 

330 

360 

386 

415 

87 

7,000,000 

129 

161 

194 

225 

257 

290 

322 

355 

387 

418 

450 

484 

87 

8,000,000 

146 

182 

218 

255 

291 

328 

364 

400 

435 

474 

510 

547 

88 

9,000,000 

164 

205 

245 

286 

328 

368 

410 

450 

492 

532 

572 

614 

88 

10,000,000 

146 

225 

270 

315 

360 

405 

450 

495 

540 

585 

630 

675 

89 

11,000,000 

198 

247 

296 

346 

395 

446 

495 

543 

592 

642 

690 

740 

89 

12,000,000 

214 

266 

320 

375 

426 

480 

534 

585 

640 

692 

750 

800 

90 

13,000,000 

231 

289 

346 

404 

464 

520 

579 

638 

694 

745 

800 

8G9 

90 

14,000,000 

246 

308 

370 

430 

494 

554 

617 

676 

740 

800 

860 

923 

91 

15,000,000 

264 

330 

396 

461 

529 

593 

660 

726 

790 

860 

922 

990 

91 

16,000,000 

278 

348 

418 

488 

556 

627 

697 

767 

832 

906 

975 

1043 

92 

17,000,000 

296 

370 

444 

520 

591 

666 

740 

810 

888 

960 

1034 

1109 

92 

18,000,000 

310 

388 

465 

541 

619 

696 

775 

852 

930 

1006 

1042 

1162 

93 

20,000,000 

345 

430 

518 

602 

689 

775 

861 

946 

1033 

1120 

1205 

1290 

93 

22,000,000 

375 

458 

560 

655 

750 

843 

990 

1030 

1123 

1266 

1310 

1406 

94 

25,000,000 

426 

532 

639 

745 

850 

959 

1065 

1173 

1278 

1381 

1491 

1596 

94 

30,000,000 

505 

631 

800 

885 

1010 

1138 

1262 

1390 

1519 

1640 

1772 

1895 

95 

35,000,000 

590 

738 

885 

1033 

1180 

1325 

1478 

1622 

1772 

1918 

2063 

2219 

95 

40,000,000 

668 

833 

1000 

1168 

1335 

1500 

1669 

1858 

2025 

2165 

2340 

2500 

96 

This  table  is  made  up  by  taking  the  column  of  efficiencies 
from  record  and  experience,  and  as  the  water  end  horse  power  is 
a  positive  matter  governed  by  the  water  pressure  and  the  quan- 
tity of  water,  the  indicated  steam  power  to  meet  the  efficiency 
stated,  is  found  by  dividing  the  water  end  horse  power  by  the 
given  percentage  in  the  table;  as,  for  example,  if  the  water  end 
horse  power  is  400  and  the  efficiency  89  per  cent  the  indicated 
power  will  be  400  divided  by  .89,  and  the  result  is  450  in  round 
numbers  as  the  steam  indicated  horse  power  of  the  pumping 
engine.  The  scale  of  per  cent  efficiencies  in  this  table  will  no 


f 

ACTUAL  CONDITIONS  OF  PUMPING  1C1 

doubt  be  considered  low  by  some,  but  it  is  safe  and  conserva- 
tive and  provides  against  a  lack  of  steam  power  in  the  machine, 
which  is  an  enemy  to  good  economy.  If  any  builder  of  pump- 
ing engines  can  produce  machinery  with  a  higher  mechanical 
efficiency  than  that  shown  in  the  table,  and  some  undoubtedly 
can,  in  the  lower  ranges  given,  then  so  much  the  better  and 
safer  for  long  continued  results. 

As  this  chapter  deals  necessarily  to  a  considerable  extent 
with  the  boiler  question,  it  will  not  be  out  of  place  perhaps 
to  refer  somewhat  more  concisely  to  that  portion  of  a  pumping 
plant.  The  higher  and  higher  steam  pressures  which  have  gone 
hand  in  hand  with  the  greater  and  greater  steam  economy  of 
the  last  ten  years  or  so  have  changed  ideas  on  boilers,  brought 
greater  horse  power  per  boiler  by  enlarging  the  pumping  unit 
and  gross  demand,  and  has  lead  to  restricting  the  dimensions 
of  the  boiler  plant  so  far  as  practicable  in  proportion  to  the 
power  developed.  Probably  for  regular  good  e very-day  effi- 
ciency, the  horizontal  return  tubular  is  as  good  as  any,  and 
better  than  most;  but,  where  large  powers  are  involved,  high 
steam  pressures  used,  the  room  required  considered,  and  in- 
cluding the  size  of  the  necessary  buildings,  a  limit  is  placed 
upon  the  consistent  size  of  the  boilers  and  units  of  this  type 
of  steam  generator.  The  writer  does  not  look  with  favor  upon 
underfired  boilers  with  shells  of  large  diameter;  and,  although 
special  and  comparatively  expensive  plants,  the  designing  of 
which  has  been  in  the  hands  of  thoughtful  and  dexterous  engi- 
neers, seem  to  demonstrate  the  feasibility  of  using  such  boilers 
occasionally,  still  in  the  long  run  and  among  the  many  plants 
built,  the  boiler  for  high  pressure,  made  up  of  parts  of  compara- 
tively small  diameters  upon  the  sectional  or  unit  principle, 
seems  to  economize  space,  buildings,  first  cost  of  the  completed 
plant,  and  other  important  particulars  in  that  line,  to  a 
very  satisfactory  degree.  And  therefore  the  writer  takes  the 
ground  that  under  present  circumstances  at  least,  considering 
unit  capacity,  gross  demands,  economy  of  construction,  con- 
venience, and  economy  of  operation,  together  with  considera- 


102  PUMPING  ENGINES 

tions  as  to  buildings  and  space  required,  the  water  tube  boiler 
fitted  with  automatic  stokers,  takes  the  lead  as  a  steam  maker 
for  water  works  pumping  plants. 

Whatever  there  is  in  economy  from  utilizing  waste  heat  in 
the  back  flue  of  the  boilers  is  a  credit  to  the  boilers  and  not 
to  the  engine,  and  of  course  reheaters  for  the  receiver  steam 
can  be  provided  and  this  steam  made  a  vehicle  for  the  trans- 
portation of  the  heat  getting  away  up  the  chimney,  if  such 
be  the  case,  back  to  the  engine,  and  made  to  do  useful  work 
there.  This  is  no  special  credit  to  any  particular  type  of  en- 
gine beyond  presenting  facilities  for  the  use  of  heat  which 
the  boilers  are  allowing  to  escape.  But  it  will  reduce  the  coal 
bills  by  turning  into  useful  work  some  of  the  heat  of  combus- 
tion unabsorbed  by  the  boiler  heating  surface. 

It  is  not  entirely  clear  why  more  of  this  practice  of  flue  re- 
heating has  not  been  done.  It  certainly  has  been  known  long 
enough.  The  writer  has  now  before  him  a  supplement  of  the 
American  Machinist  of  October,  1878,  illustrating  the  Paw- 
tucket  pumping  engine  designed  and  built  by  Geo.  H.  Corliss, 
in  connection  with  which  flue  reheating  was  very  successfully 
used  to  the  surprise  and  confusion  of  the  experts,  who  found 
from  indicator  cards  that  more  steam  apparently  camo  out 
of  the  low  pressure  cylinder  than  there  was  to  go  into  it,  before 
it  was  discovered  that  some  steam  was  added  to  the  high  pres- 
sure exhaust  by  the  boiler  flue  turning  the  condensation  into 
live  steam.  In  this  case,  the  duty  given  by  a  small  cross 
compound  engine  reached  the  very  satisfactory  figures  of  a 
little  over  133,000,000  ft.  Ibs.  with  100  Ibs.  of  coal.  Within 
the  past  five  years  the  Barr  Pumping  Engine  Company  used 
this  device  at  Haverhill,  Mass.,  also  in  connection  with  a 
moderate  sized  cross  compound  pumping  engine,  and  the  very 
best  of  authority  reports  over  150,000,000  ft.  Ibs.  duty  per 
1,000  Ibs.  of  steam,  which  at  9  Ibs.  evaporation,  a  fairly 
good  figure  for  high  pressure  boiler  work,  would  amount  to 
135,000,000  ft.  Ibs.  per  100  Ibs.  of  coal. 

Superheated  steam  and  generally  higher  steam  pressure  up 


ACTUAL  CONDITIONS  OF  PUMPING  103 

to  about  175  gauge  pressure  will  take  place  gradually,  and  that 
will  likely  mark  the  desirable  and  practicable  limits  of  the 
present  record-making  plant,  with  the  vertical  reciprocating 
steam  pumping  engine.  The  present  type  will  hold  this  line 
of  advance  stubbornly,  and  it  will  require  a  great  deal  more 
progress  than  is  evident  in  any  direction  at  the  present  time, 
1907,  to  dislodge  or  even  shake  it  materially.  Its  capital  and 
fuel  accounts  even  with  coal  at  a  moderate  price  make  a  very 
satisfactory  showing  just  now,  and  the  yearly  maintenance 
account  in  the  presence  of  good  design  and  construction  will 
not  exceed  5%  for  boilers  and  2%  for  machinery,  in  moderate 
and  good  sized  plants  where  it  is  reasonably  well  cared  for.  So 
far  as  fuel  economy  alone  is  concerned,  the  present  day  gas 
engine  is  rapidly  coming  to  the  front,  but  there  are  several 
mechanical  details  to  be  carefully  and  successfully  thought 
out,  before  gas  will  be  used  for  pumping  water  to  any  great 
extent. 

Therefore  it  looks  to  be  fairly  safe  to  plan  away  for  another 
decade  at  least,  perhaps  much  longer,  and  keep  an  eye  upon 
the  gradually  increasing  size  of  the  pumping  units  during  the 
remodeling  of  old  plants  and  the  construction  of  new  plants. 
The  perfect  plant  for  water  works  pumping  so  far  as  present 
evidence  goes,  will  apparently  involve  the  following  items: 

Water  tube  boilers. 

Mechanical  stokers. 

Natural  draught,  at  least  0.8  of  an  inch  of  water. 

Feed  water  economizer  heaters. 

Automatic  damper  regulators. 

Coal  bought  upon  the  basis  of. heat  units  and  quality. 

One  hundred   and   seventy-five   Ibs.    steam  pressure  per 
gauge. 

Moderately  superheated  steam  by  independent  apparatus. 

Modified  steam  jacketing  and  reheating. 

Smoke  flue  reheating. 

Vertical  triple  expansion  pumping  engines  of  long  stroke. 

Maximum  piston  travel,  200  ft.  per  minute. 


104  PUMPING  ENGINES 

Maximum  rotative  speed,  20  revolutions  per  minute,  or 

equivalent  cycle. 
Coal  per  indicated  horse  power  per  hour,  1  Ib.  for  large 

plants. 
Coal    per  indicated    horse    power    per    hour,   1.75    Ibs. 

for  small  plants. 

Maintenance  of  engines,  1.5%  for  large  plants. 
Maintenance  of  engines,  3%  for  small  plants. 
Maintenance  of  boilers,  5%  for  all  sizes. 

These  and  some  other  items  of  a  similar  nature  are  about 
what  a  look  ahead  discovers  as  the  coming  events  in  the  plan- 
ning, construction,  and  operation  of  pumping  plants  for  muni- 
cipal water  works. 


CHAPTER  IX 
THE  WORTHINGTON  DUPLEX  PUMPING  ENGINE 

As  regular  standard  pumping  engines,  each  kind  repeatedly 
produced  practically  alike,  and  installed  in  regular  water-works 
pumping  stations,  there  have  been  only  four  which  have  been 
built  to  an  extent  and  in  sufficient  numbers  to  fairly  entitle 
them  to  the  distinction  of  being  called  types.  These  are  as 
follows : 

The    Worthington    compound   condensing   duplex   pump- 
ing engine,  1863. 
The    Holly    quadruplex    compound    condensing    pumping 

engine,  1872. 

The  Gaskill  compound  condensing  pumping  engine,  1882. 
The    Reynolds    triple-expansion    condensing  pumping  en- 
gine, 1886. 

The  first  of  the  pronounced  types,  the  Worthington  duplex, 
non-rotative  water-works  pumping  engine,  began  to  appear 
in  1863,  designed  by  Henry  R.  Worthington  of  New  York, 
and  has  been  looked  upon  by  engineers  of  high  standing  as 
one  of  the  remarkable  inventions  of  the  times.  It  was  at  first 
built  exclusively  as  a  horizontal  engine,  but  to  meet  later  and 
present  day  requirements  and  demands  has  also  entered  the 
field  of  vertical  machinery.  Within  10  years  of  its  first  appear- 
ance, say  by  1873,  it  had  been  reduced  practically  to  a  repeated 
and  standard  type;  and  as  a  compound  condensing,  duplex, 
and  so-called  "low  duty"  engine,  had  been  installed  by  1880 
hi  about  90  pumping  stations,  with  an  aggregate  capacity  of 
over  400,000,000  U.  S.  gallons  per  day.  (See  Fig.  15.) 

The  machine  consists  of  two  complete  pumping  engines, 
simple  or  compound  as  the  case  might  be,  placed  side  by  side 

106 


100 


PUMPING  ENGINES 


WORTHINGTON  DUPLEX  PUMPING  ENGINE          107 

with  their  center  lines  parallel  with  each  other;  each  engine 
working  the  main  steam  valve  of  the  other;  these  main  valves 
being  of  the  plain  slide  variety  and  generally  fitted  with  means 
for  balancing  the  steam  pressure;  but  when  cut-off  valves 
are  used,  each  engine  operates  its  own  cut-off  mechanism.  The 
steam  jacket,  the  condenser,  the  air  pump,  and  other  primary 
features  introduced  by  Watt  were  freely  employed  in  the  de- 
sign of  this  engine.  It  is  the  simplest  form  of  machinery  with 
which  water  can  be  pumped  on  a  scale  corresponding  to  public 
water  supply  service,  and  has  only  the  necessary  steam  pistons 
with  which  to  utilize  the  heat  energy  of  the  steam,  and  the 
necessary  water  plungers  with  which  to  force  the  water  against 
the  pressure  of  the  hydraulic  load,  together  with  light  and 
simple  connecting  bars  for  keeping  the  proper  relations  between 
the  steam  and  water  ends  of  the  machine.  It  has  no  massive 
framing,  no  heavy  shafts  and  fly-wheels;  only  some  insig- 
nificant looking  connections  for  operating  the  steam  valves 
which  distributed  the  steam  to  and  from  the  places  where  it 
did  its  work.  It  was  handicapped  in  its  low  duty  form  for 
this  day  and  age  by  the  fact  that  it  could  not  expand  steam 
beyond  certain  limited  ratios,  and  if  it  could  have  retained  its 
simplicity  of  a  quarter  of  a  century  ago,  and  at  the  same  time 
greatly  increased  its  steam  economy,  there  would  have  been 
to-day  but  a  limited  place  for  the  crank  and  fly-wheel  type  of 
pumping  engine. 

Each  pair  of  pistons,  one  high  pressure  and  one  low  pressure 
of  each  of  the  tandem  compound  steam  ends,  is  coupled  to  a 
double  acting  water  plunger  by  an  extension  of  the  high  pres- 
sure piston  rod  to  a  cross  head,  into  which  is  keyed  the  plunger 
rod  leading  into  the  water  cylinder  and  so  driving  the  plunger 
directly  from  the  steam  pistons  without  the  intervention  of 
any  kind  of  mechanism  or  machinery;  hence  the  name  "direct 
acting"  which  was  first,  and  is  yet,  often  applied  to  this  type  of 
pumping  machinery.  The  front  head  of  the  low  pressure 
cylinder  and  the  back  head  of  the  high  pressure  cylinder,  are 
formed  practically  in  one  piece,  the  high  pressure  being  in  front 


108  PUMPING  ENGINES 

of  the  low  and  close  to  the  latter;  which  is  to  say  that  the  high 
pressure  cylinder  is  situated  between  the  low  pressure  cylinder 
and  the  water  end,  the  low  pressure  cylinder  and  the  water 
end  resting  directly  upon  the  foundations,  and  the  high  pres- 
sure cylinder  partially  supported  by  an  iron  column  and  partially 
from  the  low  pressure  cylinder  head.  The  low  pressure  piston 
has  two  rods,  which  pass  through  long  sleeves  or  really  ex- 
tensions of  the  low  pressure  stuffing  boxes,  outside  of  the  high 
pressure  cylinder  barrel.  The  low  pressure  piston  rods  extend 
and  are  keyed  to  the  same  cross  head  which  receives  the  high 
pressure  piston  rod,  thus  making  an  arrangement  of  three 
steam  piston  rods  at  one  side  of  the  cross  head,  and  a  single 
plunger  rod  at  the  other  side;  a  very  compact,  strong,  and 
satisfactory  form  of  construction.  In  the  very  early  and  quite 
large  engines,  the  high  pressure  and  the  low  pressure  rods  were 
coincident  with  each  other,  forming  a  single  steam  rod  passing 
from  the  low  pressure  through  a  closely  fitting  sleeve  in  the 
front  head  of  the  low  pressure  cylinder  and  so  into  the  high 
pressure,  then  out  of  the  front  head  of  the  high  pressure,  and  so 
on  to  the  main  cross  head,  to  which,  at  the  other  side,  the 
plunger  rod  was  secured. 

The  steam  and  water  ends  of  the  engine  are  connected  by 
very  simple  framing  or  cradle  bars,  as  there  are  no  pillow  blocks 
or  crank  shafts  to  provide  for.  In  the  early  engines  these 
frame  or  cradle  bars  were  simply  four  heavy  turned  and  pol- 
ished, wrought-iron  rods,  extending  from  the  high  pressure 
cylinder  heads  to  the  water  ends  or  cylinders,  and  upon  the 
upper  pair  of  bars  there  attached  the  bearings  for  the  valve 
gear.  In  later  engines  the  framing  is  composed  of  heavy  cast- 
iron  cradles  to  which  are  attached  the  steam  valve  mechan- 
ism and  other  necessary  details.  The  finished  wrought  iron 
cradle  bars  connecting  the  steam  and  water  ends,  the  steam 
cylinders  handsomely  lagged  with  dark-colored  wood,  and 
the  clean  cut,  well-designed  water  cylinders,  formed  a  sub- 
stantial, neat,  and  altogether  handsome  and  attractive  piece 
of  machinery.  No  doubt  the  early  Worthington  pumping 


HENRY    R.    WORTHiNGTON. 


f     V     OF  THE     ^\ 

I    UNIVERSITY  ) 

OF  J 

DRJJ^/ 


WORTHINGTON  DUPLEX  PUMPING  ENGINE         109 

engines  of  goodly  size,  constructed  as  above,  formed  a  type 
of  machinery,  which  for  grace  and  appropriateness,  has  never 
been  surpassed  in  the  line  of  water-works  pumping  machinery. 
The  writer  was  at  the  Newton,  Mass.,  pumping  station  in  July 
of  1905,  where  one  of  the  old  time  Worthington  pumping  engines 
of  7,000,000  U.  S.  gallons  capacity  was  at  work,  and  has  been 
at  work  over  27  years  pumping  water  for  public  supply,  and 
was  at  the  time  of  this  visit  working  against  a  water  load  of 
about  100  Ibs.  pressure.  No  quieter,  smoother  running,  or 
more  satisfactory  machinery  could  possibly  be  found  for  the 
purpose  of  pumping  water,  and  it  is  now  only  outdated  on 
account  of  the  fuel  burned  for  regular  work,  but  is  held  in  re- 
serve when  other  machinery  requires  attention.  This  early 
type  of  pumping  engine  has  always  been  noted  for  its  smooth- 
ness of  action  in  the  work  of  pumping  against  a  heavy  head 
and  under  high  pressure  loads,  and  seems  to  work  as  perfectly 
and  with  as  little  noise  as  under  lighter  heads;  this  no  doubt 
being  largely  due  to  the  fact  that  the  engine  is  at  all  times 
almost  completely  under  the  control  of  the  water  column,  the 
engine  seemingly  doing  nothing  further  than  to  furnish  the 
power  necessary  to  overcome  the  water  pressure,  while  so  far 
as  the  flow  of  the  water  is  concerned,  and  the  actual  timing  of 
the  movements  of  the  plungers  and  pistons,  the  hydraulic 
action  is  in  control  of  the  main  pumps. 

The  main  pumps  are  of  the  inside  ring  type,  secured  directly 
in  line  with  the  steam  cylinders,  so  that  the  force  and  resistance 
of  the  pumping  is  in  the  same  center  line,  making  the  engine 
self-contained  so  far  as  concerns  the  work  to  be  done  and  the 
material  used  in  construction.  The  outlet  from  the  force 
chambers  are  90°  bends  turned  towards  each  other  and  are 
joined  by  a  three-way  casting  upon  which  is  mounted  the  air 
chamber,  only  one  air  chamber  being  used,  but  it  is  situated 
at  a  very  advantageous  point  with  reference  to  the  delivery 
of  the  water  alternately  from  the  two  water  cylinders.  From 
the  outer  opening  of  this  three-way  casting,  the  force  main 
begins,  and  is  lead  down  through  the  floor  and  so  out  of  the 


110 


PUMPING  ENGINES 


building.  The  pump  chamber,  or  water  cylinder  proper,  has 
at  the  middle  of  its  length  an  inside  flange  to  which  is  bolted 
the  ring  or  sleeve  through  which  the  plunger  works,  and  so  does 
the  pumping.  The  valve  decks  or  flat  surfaces,  properly  ribbed 

for  strength,  are  situated 
in  horizontal  planes  directly 
above  and  below  the  water 
plunger,  and  the  brass  valve 
seats  are  either  screwed  into, 
or  are  bolted  onto  the  valve 
decks;  the  valves,  see  Fig.  16, 
are  rubber  discs  of  moderate 
or  small  size,  moving  verti- 
cally upon  brass  stems  and  are 
controlled  either  by  weights, 
as  in  the  early  practice,  or  by 
springs  as  in  the  later  work. 
Immediately  below  and  above 
the  water  cylinder  are  situ- 
ated the  suction  and  force 
chambers,  respectively;  the 
former  joined  by  a  cross  suc- 
tion with  easy  bends  for  the 
flow  of  the  incoming  water, 
and  at  the  outer  extremity 
of  the  cross  pipe  is  located 
the  main  suction  pipe  which 
usually  drops  vertically  into 
the  pump  well  from  which 

Fig.  16.-  Standard  Briber  Valve  and  Seat.  the  ^S1116   draws  its  Supply. 

The  suction  pipe  is  some- 
times extended  to  the  outside  of  the  building,  and  the  machine 
pumps  from  a  well  located  at  some  convenient  point  near  the 
walls,  or  not  to  exceed,  say  30  feet  preferably,  although  the 
writer  has  located  and  used  pump  wells  60  feet  away  from 
the  building  with  satisfactory  results,  provided  the  size  of  the 


WORTHINGTON  DUPLEX  PUMPING  ENGINE        111 

suction  pipe  was  large  enough  to  keep  the  friction  of  flow  down 
to  a  point  amounting  practically  to  nothing,  or  at  least  an 
acceptable  minimum. 

The  force  chambers  are  bolted  to  the  upper  surface  of  the 
water  cylinders  which  form  the  discharge  valve  decks,  and 
from  the  middle  of  the  length  of  each  force  chamber  the  water 
is  discharged  through  an  appropriate  opening  formed  into  a 
flange  for  the  reception  of  the  90°  bends  already  referred  to. 
The  force  chamber,  the  water  cylinder,  and  the  suction  cham- 
ber are  provided  with  handholes  and  manholes  for  inspecting 
and  giving  proper  attention  to  the  interior  of  the  pump  when 
occasion  requires,  these  holes  being  closed  during  operation 
by  bolted  plates,  the  largest  ones  being  provided  with  hinges 
to  facilitate  handling.  The  flow  of  the  water  into  and  through 
the  suction  chamber  and  valves,  directly  upward  through  the 
discharge  valves  and  force  chamber,  and  so  on  into  the  force 
main,  with  the  liberal  dimensions  employed  in  this  type  of  en- 
gine even  40  years  ago,  leaves  nothing  to  be  desired  in  the  way 
of  low  rate  of  water  friction  and  high  percentage  of  hydraulic 
efficiency. 

The  tandem  compound,  steam  end  of  the  engine,  is  a  regular 
reciprocating  steam  engine,  with  steam  jacketed  cylinders, 
with  pistons  working  in  couples,  one  high  and  one  low  pres- 
sure, and  with  plain  balanced  slide  valves  located  at  the  top  of 
the  cylinder  barrel.  The  pistons  work  in  the  same  axial  line 
and  the  valve  seats  are  in  the  same  plane,  the  high  pressure 
seat  being  raised  the  difference  in  the  half  diameter  in  the  two 
cylinders,  so  as  to  use  a  practically  continuous  valve  stem  for 
both  main  valves;  the  balancing  piston  and  supporting  column 
is  directly  over  the  steam  chest ;  and  the  entire  design  has  proved 
itself  by  years  of  usefulness  to  be  of  the  very  highest  type 
of  means  to  suit  the  ends  sought. 

The  air  pumps,  four  in  number  generally,  although  some- 
times two  are  used,  as,  for  example,  in  the  Newton  engine, 
are  placed  in  a  small  pit  formed  by  the  space  between  the  water 
and  steam  ends  of  the  machine,  and  are  driven  by  a  tri- 


112 


PUMPING  ENGINES 


m. 


WORTHINGTON  DUPLEX  PUMPING  ENGINE        113 

angular  bell-crank  lever  connected  to  the  main  cross  head,  and 
the  shafts  of  the  bell  cranks  are  utilized  for  giving  motion  to 
the  valve  gear.  The  condenser  is  situated  directly  beneath  the 
high  pressure  cylinders  and  half  way  between  the  two,  upon 
the  lower  portion  of  the  foundation,  making  it  possible  to  have 
a  very  short  exhaust  pipe  from  the  low  pressure  cylinder. 

The  steam  pistons  are  simple  and  of  the  well  known  cast- 
iron  ring  packing  variety,  with  generous  bearing  surfaces,  as 
is  demonstrated  by  their  long  life  and  usefulness  in  every-day 
operation.  The  water  plungers  are  generally  hollow  and  aim 
to  be  water-tight,  so  as  to  secure  partial  flotation,  but  it  is 
doubtful  if  they  remain  empty  any  great  length  of  time,  and 
indeed  it  matters  little  whether  they  do  or  not,  as  the  friction 
and  wear  could  not  be  a  very  material  matter  in  any  event. 
This  form  of  plunger  will  keep  practically  water-tight  through 
the  sleeve  or  ring,  or  as  water-tight  as  most  plungers  in  average 
clear  water  for  long  periods  of  time,  as  is  evident  from  known 
results.  One  case  known  to  the  writer  was  at  Toledo,  Ohio, 
where  the  engines  had  been  on  stand-pipe  service  for  12  years, 
which  is  really  direct  service  in  the  sense  that  there  is  no  storage, 
and  the  machinery  must  run  continuously;  the  water  was  not 
clear  but  contained  a  fine  clay  silt  extremely  difficult  of  sedi- 
mentation, and  upon  test  the  plungers  leaked  so  little  under 
80  Ibs.  pressure  with  one  pump  head  removed,  that  it  was 
difficult  to  make  accurate  measurements  of  the  quantity. 

The  original  Worthington  pumping  engine  possessed  the 
qualifications  for  the  first  duty  of  a  pumping  engine  to  "  PUMP 
WATER,  "  and  to  do  so  continuously  with  the  least  practicable 
interruption,  to  a  degree  which  has  never  been  equaled  by 
any  machine  ever  produced  for  the  purpose;  and  not  even  by 
the  improved  or  high  duty  engine  of  the  same  type.  It  holds 
the  record  for  durability.  But  its  steam  economy  was  limited 
to  the  possibilities  of  expanding  steam  at  full  stroke  through 
two  cylinders  of  different  diameters  alone,  and  without  the  high 
expansion  ratios  possible  with  the  use  of  cut-off  valves.  It 
had  apparently  reached  the  economic  limit  with  compound 


114 


PUMPING  ENGINES 


WORTHINGTON  DUPLEX  PUMPING  ENGINE         115 

cylinders  alone  without  cut-off,  and  with  the  steam  pressures 
usually  employed.  But,  of  course,  the  question  arose  nat- 
urally enough  in  time,  can  this  machine,  so  satisfactory  on  the 


Fig.  19. — Worthington  Compensating  Cylinder  Diagram. 

main  point,  that  of  certainly  pumping  water,  be  improved  in 
its  economy  of  steam  without  giving  up  its  best  features  of 
design?  And  this  question  has  been  answered  by  the  introduc- 
tion of  the  high  duty  Worthington  engine,  in  1886,  as  shown 
in  Fig.  17  in  perspective,  and  in  section  in  Fig.  18,  although 


116 


PUMPING  ENGINES 


w 

I 


0? 

fee 


OF  THE 

UNIVERSITY 


bo 

£ 


WORTH1NGTON  DUPLEX  PUMPING  ENGINE          117 

some  of  the  simple  effectiveness  has  been  sacrificed,  but  not 
seriously  so.  And  so  it  turns  out  that  the  argument  of  low 
first  cost  and  low  duty,  against  the  argument  of  higher  first 
cost  and  higher  duty,  has  been  nullified  by  simplifying  and  re- 
ducing the  cost  of  the  crank  and  fly-wheel  pumping  engine; 
and  by  complicating  and  increasing  the  cost  of  the  non-rotative 
or  direct-acting  pumping  engine;  both  results  being  forced 
upon  each  type  by  the  struggle  with  each  other  for  commercial 
supremacy,  and  the  final  result  being  that  both  types  now 
meet  on  common  ground  as. to  the  commercial  situation. 

In  the  newer  Worthington  engine  the  most  prominent  fea- 
tures remain  the  same  as  in  the  older  engine,  as  to  general 
arrangement  of  steam  and  water  cylinders,  but  a  device  has; 
been  added  which  is  called  the  high  duty  attachment  and 
consists  of  a  pair  of  small,  oscillating  water  cylinders  attached1 
to  some  place  in  the  framing,  sometimes  beyond  the  outer- 
ends  of  the  main  water  cylinders,  and  sometimes  between  the 
steam  and  water  ends  of  the  engine.  Connections  are  made 
through  the  trunions  of  these  oscillating  cylinders  with  a  hy- 
draulic accumulator,  which  in  turn  is  connected  with  the  water 
pressure  in  the  force  main,  and  by  this  means  the  pressure  on 
the  inner  ends  of  the  plungers  in  the  oscillating  cylinders  is- 
maintained  in  close  relation  with  the  pressure  in  the  fore 
main  against  which  the  engine  is  working.  These  plungers- 
with  their  swinging  motion,  which  constantly  changes  the 
angle  with  the  center  line  of  the  engine,  resist  the  advance  of 
the  steam  pistons  at  the  beginning  of  the  stroke  just  when 
the  initial  steam  pressure  is  too  much  to  drive  the  water  plungers 
against  the  load,  and  helps  the  steam  pistons  finish  their  stroke 
when  the  expansion  has  brought  the  steam  pressure  down  to  a 
point  which  is  too  low  to  drive  the  water  plungers  without 
some  kind  of  assistance.  In  short,  the  oscillating  plungers 
change  from  resistance  to  assistance  during  each  stroke  of 
the  engine  to  meet  the  varying  pressure  given  out  by  highly 
expanding  steam,  and  which  the  older  engine  did  not  have  to 
struggle  with.  Fig.  19  shows  a  diagram  which  represents, 


118 


PUMPING  ENGINES 


Fig.  23.— Worthington  Vertical  Triple,  High  Duty. 


I 

WORTHINGTON    DUPLEX    PUMPING    ENGINE        119 

this  action  of  the  oscillating  or  compensating  plungers  and 
cylinders.  Low  expansion,  as  in  the  older  engine,  meant  low 
duty,  that  is,  in  the  neighborhood  of  65,000,000  ft.  Ibs.  per 
1,000  Ibs.  of  steam;  and  high  expansion,  as  in  the  newer  engine, 
means  high  duty,  that  is,  100,000,000  ft.  Ibs.  per  1,000  Ibs.  of 
steam,  and  upward.  The  resistance  and  assistance  given  out 
by  the  compensating  cylinders  is  just  what  the  fly-wheel  gives 
to  the  crank  engine,  only  in  one  type  it  is  done  with  water 
pressure,  while  in  the  other  type  with  the  weight  of  cast  iron. 
Each  pair  of  oscillating  or  compensating  cylinders  are  directly 
opposite  the  engine  center  line  and  therefore  act  in  concert 
with  each  other,  and  relieve  the  cross  head  in  which  they  work 
in  sockets  of  any  cross  frictional  resistance  or  unbalanced 
lateral  strains. 

The  alterations  from  the  old  to  the  new  were  cautiously  made, 
and  at  first  with  as  few  changes  as  possible;  and  even  at  that, 
unknown  difficulties  in  construction  were  bound  to  be  met  in 
such  an  unexplored  field.  At  first  the  plain  slide  valve  on  the 
steam  cylinders  was  retained,  and  cut-off  valves  added.  Then 
the  large  slide  valves  were  discontinued  and  what  might  be 
called  the  Corliss  type  substituted,  the  first  important  high  duty 
engine  being  a  15,000,000  gallon  machine  for  Chicago  in  1889, 
with  all  of  the  valves  placed  at  the  top  line  of  the  horizontal 
cylinders,  using  four  valves,  but  having  two  main  valves  for 
induction  and  exhaust,  and  directly  over  these,  two  cut-off 
valves,  which  cut  off  the  steam  after  the  main  valves  had  ad- 
mitted it,  and  then  drew  back  out  of  the  way  in  time  for  the 
next  admission  by  the  main  valve.  The  exhaust  was  accom- 
plished through  a  cavity  in  the  under  side  of  the  main  valve, 
the  same  practically  as  in  a  plain  slide  valve. 

This  change  in  the  steam  valves  immediately  reduced  the 
clearance  or  waste  room,  removed  the  necessity  of  having  the 
valves  in  the  same  plane  because  radius  rods  were  submitted 
for  ordinary  valve  stems  as  before,  and  improved  the  steam 
economy.  Finally  the  four  valves  were  placed  at  the  four 
corners  of  the  cylinder,  as  in  the  drop  cut-off  arrangement, 


120  PUMPING  ENGINES 

and  were  worked  by  a  sort  of  compound  wrist  plate  for  which 
a  motion  was  obtained  peculiar  to  the  direct  acting  machine. 
The  operation  of  these  steam  valves  was  obtained  by  positive 
motions,  as  it  was  clear  that  a  releasing  and  drop  cut-off  would 
not  be  safe  or  regular  on  this  type  of  engine.  Any  point  of 
cut-off  can  be  secured  by  changing  the  location  of  a  sliding 
block;  the  operation  is  without  noise,  and  the  various  levers, 
rods,  and  pins  have  easy  work  and  consequently  little  wear. 

Fig.  20  shows  a  compound  condensing,  high  duty,  hori- 
zontal Worthington  engine,  with  attached  air  pumps  and  jet 
condenser,  accumulator,  compensating  cylinders,  valve  motion, 
reheaters,  and  other  details.  A  horizontal  triple  expansion 
engine  is  shown  in  Fig.  21. 

A  vertical  triple  expansion  engine  of  20,000,000  U.  S.  gallons 
daily  capacity  is  shown  in  Fig.  23,  and  exemplifies  the  very 
great  departure  which  time  and  the  demands  for  larger  units, 
high  duty,  and  other  considerations  have  brought  about  since 
the  early  engines  of  the  low  duty  horizontal  type  were  built  and 
held  the  front  of  the  stage  for  water-works  pumping  machinery. 

The  Worthington  water-works  pumping  engine  has  also 
appeared  as  a  low  duty  triple  expansion  machine,  which  con- 
sists of  the  original  compound  engine  with  an  additional  pair 
of  steam  cylinders  attached,  but  without  the  compensating 
cylinders;  the  added  cylinders  being  generally  in  front  of  the 
former  high  pressure  cylinders,  thus  making  the  new  ones  the 
high  pressure,  the  former  high  pressure  into  intermediate  cylin- 
ders, and  with  the  low  pressure  cylinders  remaining  as  formerly. 
This  form  hardly  approaches  the  dignity  of  a  distinct  type  but 
rather  should  be  called  a  class,  because  it  involves  the  principal 
features  of  the  real  type.  It  is  only  applicable  to  moderate 
capacities,  it  generally  paying  better  to  have  a  regular  high 
duty  compound  when  the  required  capacity  gets  up  to  say 
5,000,000  gallons  per  day  and  over.  A  cut-off  is  usually  ap- 
plied to  the  high  pressure  cylinders  and  then  a  rather  high 
rate  of  reciprocation  employed  so  as  to  get  the  benefit  of  the 
momentum  of  the  moving  parts  to  finish  the  stroke,  which  of 


WORTH INGTON  DUPLEX  PUMPING  ENGINE         121 

course  suggests  that  the  direct  acting  engine  depending  purely 
upon  the  force  of  the  steam  is  slightly  invading  the  field  of 
the  crank  and  fly-wheel  machine,  and  that  perhaps  a  simple 
cross  compound  engine  of  the  wheel  type  might  be  just  as  well 
for  the  work.  This  low  duty  triple  expansion  Worthington 
pumping  engine  is  shown  in  Fig.  22,  which  indicates  the  general 
features  and  many  of  the  details  of  this  form  of  the  well  known 
direct  acting  machine. 

Up  to  1886,  when  the  introduction  of  the  high  duty  engine 
had  begun,  the  original  Worthington  type  of  water-works 
engines  known  as  low  duty  engines,  had  reached  250  in  number 
with  an  aggregate  daily  capacity  of  about  1,000,000,000  U.  S. 
gallons  per  24  hours,  the  engines  varying  in  capacity  from 
500,000  to  25,000,000  gallons  per  day  with  an  average  of 
4,000,000  gallons  per  24  hours. 

From  1886  to  1906  there  have  been  produced  about  225 
pumping  engines  of  the  high  duty  class,  with  an  aggregate 
capacity  of  2,250,000,000  U.  S.  gallons  per  24  hours;  or  about 
225  engines  with  an  average  daily  capacity  of  10,000,000  gallons, 
and  varying  from  3,000,000  to  40,000,000  gallons  per  24  hours. 


CHAPTER  X 
THE  HOLLY   QUADRUPLEX  PUMPING   ENGINE 

THE  Holly  quadruple x  pumping  engine  was  designed  to 
meet  an  existing  but  a  novel  want  at  the  time  of  its  first  con- 
struction. A  direct  system  of  water  supply  had  been  built 
and  put  into  operation,  in  which  water  was  distributed  through 
pipes  laid  hi  the  streets  for  the  purpose  of  protection  against 
fires;  and  by  a  direct  system  is  meant  a  closed  circuit  of  water 
pipes  wherein  the  water  pressure  is  raised  and  maintained  at  any 
certain  pressure,  and  where  there  is  no  storage  of  water  beyond 
what  is  contained  in  the  pump  well  and  the  supply  flowing  to 
such  well. 

About  1866  the  first  of  these  direct  systems  was  established 
at  Lockport,  N.  Y.,  by  Birdsill  Holly,  with  a  mile  of  cast-iron 
water  pipes,  and  a  rotary  pump  operated  by  a  water-wheel, 
the  plant  designed  for  fire  service  only.  Two  years  later  a 
similar  system  was  built  at  Auburn,  N.  Y.,  in  which  a  domestic 
supply  was  combined  with  the  protection  against  fire;  both 
these  systems  being  driven  by  means  of  water  power.  Of 
course  the  enlargement  of  such  an  important  idea  soon  carried 
it  beyond  the  reach  of  a  single  means  of  applying  power,  and 
that  means  such  a  restricted  one,  so  that  before  very  long  the 
question  of  the  application  of  steam  power  which  could  be 
located  almost  anywhere,  came  naturally  enough  into  the  prop- 
osition. And  steam  having  once  entered  the  waiting  door,  the 
study  of  fuel  economy  was  of  course  inevitable. 

The  first  attempts  at  steam  power  for  this  kind  of  water 
works,  somewhere  late  in  the  sixties,  were  in  the  line  of  a  steam 
engine  driving  a  shaft,  and  from  which  there  were  driven  a 
series  of  gang  pumps  consisting  of  six  single  acting  pumps 

122 


BIRDSILL    HOLLY- 


OF  THE 

UNIVERSITY 

»     OF 


HOLLY    QUADRUPLEX    PUMPING    ENGINE          123. 

arranged  to  operate  in  regular  succession,  the  idea  of  units  or 
increments  applied  so  that  the  lack  of  uniform  delivery  per- 
fectly natural  to  the  domestic  supply  could  be  practically  met, 
seemingly  an  early  detail  of  this  system  and  properly  so,  as 
later  experience  fully  demonstrated.  In  conjunction  with  these 
gang  pumps  there  was  used  a  rotary  pump  known  as  the 
Holly  Rotary  Pumping  Engine  and  Fire  Pump;  this  fire  pump 
being  used  only  as  an  auxiliary  in  case  of  fire  beyond  the  capa- 
bilities of  the  regular  gang  pumps.  Over  twenty  water-works 
were  fitted  out  with  the  gang  and  rotary  pumping  machinery, 
and  at  that  early  day  in  the  development  of  public  water- works 
no  doubt  provided  good  and  ample  service,  considering  all  of 
the  circumstances  and  the  unknown  road  reaching  out  ahead 
of  the  investigator,  inventor,  and  investor.  The  first  duty  of 
the  pumping  engine  was  to  pump  water,  of  course;  for  with 
plenty  of  water,  danger  could  be  avoided  even  though  accom- 
panied with  moderate  inconveniences.  But  the  engine  had 
to  do  some  other  things  which  were  not  completely  appreciated 
by  competitors  who  looked  at  the  single  item  of  pumping.  And 
so  it  came  about  that  economy  of  steam  and  fuel  went  hand  in 
hand  with  accommodation  to  the  conditions,  and  so  improve- 
ment after  improvement  was  introduced,  and  the  next  step 
after  the  gang-rotary  combination  was  the  introduction  of 
the  Holly  Quadruplex  Pumping  Engine  for  the  closed  system 
of  water-works  distribution,  in  1871  and  1872,  which  was  es- 
pecially adapted  to  both  domestic  and  fire  service  to  a  very 
remarkable  t degree,  and  superseded  both  the  gang  and  rotary 
pumps.  The  first  of  this  type  was  placed  in  the  Dunkirk,  N.  Y., 
pumping  station,  and  was  designed  as  an  engine  with  four 
straight  condensing  steam  cylinders;  but  in  1874  the  machine 
had  taken  a  step  forward  and  appeared  at  Rochester,  N.  Y.,  as 
a  regular  compound  condensing  pumping  engine  of  2,000,000 
gallons  daily  capacity. 

The  Holly  quadruplex  pumping  engine  is  a  crank  and  fly- 
wheel engine,  probably  so  named  to  indicate  a  machine  a 
point  or  two  better  than  the  duplex  machine  then  in  the  market 


124 


PUMPING  ENGINES 


•a 
& 


ai 


HOLLY  QUADRUPLEX  PUMPING  ENGINE 


125 


at  least  in  the  mind  of  its  inventor;  it  is  shown  in  perspec- 
tive in  Fig.  24,  and  in  outline  sectional  elevation  in  Fig.  25. 
There  are  four  steam  cylinders,  the  center  lines  through  which 
are  at  an  angle  of  45  degrees  from  the  horizontal;  and  four 
pumps,  one  of  the  pumps  below  and  in  line  with  each  steam 
cylinder.  The  general  or  main  framing  is  heavy  and  strong, 
and  is  formed  somewhat  like  a  letter  A,  one  frame  at  each  side 
of  the  engine.  At  the  top  or  point  of  this  A-frame  is  located 


3496. 


TT-  "1 

Fig.  25.  —  Holly  Quadruples  Pumping  Engine,  Sectional. 


the  main  pillow  blocks  or  bearings  for  the  crank  shaft,  and 
this  shaft  extends  across  the  machine  from  one  frame  to  the 
other,  carrying  at  its  mid-length  the  fly-wheel  which  is  made 
of  moderate  weight  so  as  to  respond  quickly  to  demands  for 
changes  in  the  speed  of  the  engine  and  the  variations  in  the 
quantity  of  water  to  be  pumped,  as  this  type  of  pumping  engine 
was  especially  designed  for  the  "direct  system,"  sometimes 
called  the  "Holly  system,"  wherein,  as  already  pointed  out, 
there  exists  no  storage  of  water,  the  entire  supply  with  all  of 
its  -fluctuations  being  delivered  into  the  distributing  system 
according  to  the  demands  of  the  moment. 


126  PUMPING  ENGINES 

This  engine  was  mostly  used  in  the  flat  portions  of  the  middle 
western  states  where  no  hills  existed  for  storage  and  distribu- 
ting reservoirs,  or,  where  hills  did  exist,  the  cost  of  a  reservoir 
was  deemed  out  of  the  question,  in  the  construction  of  new 
water-works  at  a  time  in  the  development  of  the  country  when 
such  conveniences  as  water  supplies  were  something  com- 
paratively new..  The  following  description  will  give  a  general 
idea  of  this  machine: 

At  each  end  of  the  main  shaft  there  is  secured  a  disc  crank, 
with  one  crank  pin  in  each  crank  common  to  a  pair  of  the  cylin- 
ders and  pumps,  the  crank  pin  for  one  of  the  pair  of  cylinders 
being  located  135  degrees  in  advance  of  the  crank  pin  for  the 
opposite  pair  of  cylinders,  so  that  8  impulses  are  obtained  at 
each  revolution  of  the  fly-wheel,  thereby  producing  a  very 
steady  flow  of  water.  This  feature  is  especially  desirable  in 
a  closed  system  of  distribution  pipes,  and  at  very  slow  speed; 
not  only  for  the  sake  of  uniform  pressure,  but  also  on  account 
of  a  steady  rate  of  revolution  of  the  engine  at  whatever  speed 
was  necessary,  which  is  conducive  at  slow  and  varying  speeds 
to  the  best  economical  results  under  naturally  bad  steam  con- 
ditions. This  principle  of  8  impulses  per  revolution  has  been 
used  later  in  large  generating  engines  for  electric  railroad  power, 
as,  for  example,  in  the  power  station  of  the  Manhattan  Elevated 
Railway,  and  for  the  New  York  Subway  power  station,  where 
engines  of  7,500  nominal  horsepower  have  been  installed;  the 
results  of  the  90  degree  angle  of  steam  cylinders  and  the  135 
degree  angle  of  crank  pins,  being  the  reduction  of  the  fly-wheel 
element,  and  an  extremely  uniform  rate  of  revolution  with  very 
smooth-running  engines.  This  principle  of  engine  construction 
is  also  followed  in  the  engines  of  the  steamboat  "Priscilla"  of 
the  Fall  River  Line,  and  the  three-throw  crank  motion  is 
found  in  the  new  Hudson  River  Day  Line  steamboat  "  Hendrick 
Hudson,"  in  all  of  which  cases  steady  and  uniform  revolutions 
at  whatever  speed  the  engine  may  be  making,  is  desirable. 

The  main  pumps  of  the  quadruplex  engine  are  of  the  piston 
pattern,  secured  directly  in  line  with  the  steam  cylinders  so 


HOLLY  QUADRUPLEX  PUMPING  ENGINE  127 

that  the  force  and  resistance  of  the  pumping  are  in  the  same 
center  lines,  thus  making  the  pumping  engine  self-contained 
with  reference  to  the  work  it  has  to  do.  Each  pump  has  its 
own  air  chamber,  situated  at  the  highest  point  of  the  angle 
formed  by  the  sloping  position  of  the  pump  castings,  and  are 
most  effective  in  their  operation.  The  suction  and  force  cham- 
bers are  above  and  below  the  pump  barrels,  and  the  seats  for 
the  water  valves  are  set  at  an  angle  of  45  degrees  to  the  center 
line  of  the  pump,  so  that  when  the  pump  is  in  position  on  the 
engine,  the  valve  seats  become  horizontal.  These  water-valve 
seats  are  arranged  in  the  deck  form,  one  deck  in  each  pump 
for  suction  valves,  and  one  deck  for  discharge  valves;  the  flow 
of  the  water  being  accomplished  with  very  little  deflection  from 
the  natural  course  from  suction  to  discharge  chambers. 

The  pump  barrel  proper  is  an  independent  piece  securely 
bolted  to  a  rib  which  divides  the  pump  chamber  into  two 
portions  corresponding  to  the  two  ends  of  the  double-acting 
pump.  The  pump  barrels  and  pistons  may  be  readily  re- 
moved, repaired,  or  replaced,  practically  without  throwing  the 
engine  out  of  service,  and  as  there  are  four  main  pumps  it  will 
be  seen  that  this  machine  is  especially  adapted  to  direct  ser- 
vice, and  where  it  is  impossible  to  have  reserve  engines  on 
account  of  cost;  it  being  remembered  that  the  Quadruplex  was 
introduced  in  the  early  stages  of  water-works,  and  very  often 
the  total  cost  of  the  system  had  to  be  closely  reckoned,  in  order 
that  any  system  could  be  had  at  all.  It  is  pretty  safe  to  say 
that  no  other  pumping  engine  has  been  so  carefully  studied  to 
adapt  it  to  the  necessities  and  wants  of  the  water  consumer, 
and  to  meet  conditions  as  they  actually  existed  in  the  direct 
service  or  closed  system  of  pipes.  The  cross-connecting  pipes 
for  suction  and  for  delivery  were  carefully  arranged  both  as  to 
position  and  necessary  shut-off  valves,  so  that  any  of  the  four 
main  pumps  could  be  taken  out  of  the  work  or  off  of  the  engine 
with  little  or  no  interruption  of  the  service.  Therefore,  it  will 
be  seen  that  the  builders  of  the  quadruplex  pumping  engine, 
instead  of  insisting  what  the  users  of  water  ought  to  do,  or  not 


128  PUMPING  ENGINES 

to,  they  recognized  the  helplessness  of  their  position,  and  made 
the  engine  do  what  was  necessary  to  practically  meet,  to  a, 
reasonable  extent,  all  and  every  demand  where  pressure  and 
quantity  of  water  were  involved;  and  in  this,  as  time  has  passed, 
the  cool  and  careful  historian  must  say  that  they  succeeded. 

The  engine  proper,  or  the  steam-power  end  of  the  machine,  is 
a  regular  reciprocating,  crank  and  fly-steam  engine,  with  guides 
and  connecting  rods  not  unlike  those  of  the  locomotive.  An 
auxiliary  connecting  rod  attached  to  one  of  the  crank  pins 
operates  the  air  pump  for  the  condensing  apparatus;  the  air 
pump  being  driven  by  means  of  a  rocking  beam  and  shaft,  the 
beam  not  only  driving  the  air  pump  but  also  two  boiler  feed 
pumps,  one  of  which  takes  its  water  supply  from  the  overflow 
from  the  air  pump,  and  the  other  taking  the  water  of  conden- 
sation from  the  steam  jackets,  and  sending  it  to  the  boilers. 

The  connections  between  the  steanfand  water  pistons  are  by 
means  of  rods  and  keys  in  the  usual  manner  of  securing  such, 
rods,  but  there  is  an  intermediate  coupling  between  the  steam 
and  water  rods  for  facilitating  the  taking  off  and  putting  on  to 
the  work,  more  or  less,  of  the  pumps  as  the  case  might  require. 
The  steam  piston  has  special  arrangements  for  saving  time  in 
adjustment;  the  piston  packing  is  usually  of  the  regular  cast- 
iron  ring  variety,  set  out  by  means  of  steel  springs;  and  the  set 
screws  for  adjusting  these  springs  project  beyond  the  face  of 
the  piston  so  that  the  packing  rings  may  be  adjusted  through 
handholes  in  the  lower  cylinder  head,  by  simply  removing  the 
bonnets.  This  is  only  one  of  the  many  devices  provided  for 
easily,  promptly,  and  quickly  meeting  the  inevitable  manipu- 
lation necessary  in  all  kinds  of  machinery,  but  which  in  the 
case  of  a  public  water  supply  must  be  done  as  nearly  as  possible 
without  interruption.  Now  cities  and  towns  are  older  and 
more  mature,  and  the  water  works  question  is  an  old  one  and 
familiar  to  all;  and  in  the  natural  growth,  older  engines  form- 
ing reserves,  the  necessities  are  removed  which  existed  forty 
years  ago,  when  only  one  engine  could  be  afforded,  and  that, 
one  was  all  and  everything  to  the  plant. 


HOLLY  QUADRUPLEX  PUMPING  ENGINE  129 

The  arrangement  of  the  steam  and  exhaust  pipes  is  such  that 
the  steam  can  be  utilized  in  several  ways:  Steam  directly 
from  the  boilers  can  be  admitted  to  all  of  the  cylinders,  and 
exhaust  into  the  condenser;  or,  steam  from  the  boilers  can  be 
admitted  to  only  one  cylinder,  and  thence  exhaust  into  the 
other  three,  and  then  sent  to  the  condenser.  So  that  four 
straight  condensing  engines,  a  compound  with  one  high  pres- 
sure cylinder  and  three  low  pressure  cylinders,  a  triple  expan- 
sion, or  a  quadruple  expansion  engine,  can  be  formed  and 
operated  at  will.  But  on  direct  service,  the  ultra-refinements 
possible  to  reservoir  work  where  the  engine  can  run  at  full 
speed  or  nearly  so,  are  not  profitable,  and  cannot  be  utilized 
by  taking  advantage  of  the  multiple  features  possible  in  the 
quadruplex  engine.  The  pumping  and  distribution  of  water 
takes  first  place  in  the  direct  system,  and  extreme  steam 
economy  is  'secondary.  Even  to-day,  on  electric  railway  ser- 
vice, the  cross  compound  engine  is  not  of  so  high  economy  as 
the  triple  machine,  but  it  is  better  adapted  to  take  care  of  the 
"peak"  of  the  load,  and  the  better  of  the  two  in  all-round  per- 
formance; it  is  an  unconscious  reflection  of  the  qualifications 
of  the  early  Holly  pumping  engines  to  meet  variable  demands. 

In  the  quadruplex  pumping  engine  the  steam  valve  gear  of 
each  cylinder  consists  of  one  slide  valve,  which  with  its  steam 
chest  and  valve  stem  also  resembles  the  locomotive  and  the 
early  steam  engines  before  the  advent  of  the  automatic  cut- 
off. A  double  poppet  valve  in  the  steam  chest  is  used  as  a 
cut-off  valve  back  of  and  above  the  main  valve,  and  is  operated 
by  means  of  a  spiral  cam,  this  cam  being  controlled  in  a  motion 
lengthwise  of  its  revolving  shaft  so  as  to  vary  the  point  of 
suppression  of  the  steam  entering  the  cylinder.  The  variation 
of  admission  and  cut-off  of  the  entering  steam  is  from  nothing 
to  full  stroke,  and  this  full  stroke  range  of  cut-off  is  necessary  to 
the  proper  regulation  of  such  slow  and  variable  moving  pump- 
ing machinery  working  upon  a  closed  circuit  of  pipes.  The 
means  and  method  of  adjusting  the  cam  to  the  desired  point 
corresponding  to  the  work  needed  to  be  done  by  the  engine, 


130  PUMPING  ENGINES 

are  very  important  features  of  the  Holly  pumping  apparatus; 
and  the  automatic  regulator  provided  for  the  purpose,  in  fairly 
good  hands,  or  in  as  good  hands  as  ought  to  be  found  in  a  public 
pumping  station,  seems  to  be  excellently  adapted  to  the  work. 
The  regulator  is  connected  to  the  water  main  so  that  any 
change  in  water  pressure  is  promptly  met  by  a  corresponding 
adjustment  of  the  steam  supply,  resulting  in  a  practically  uni- 
form water  pressure  with  a  widely  varying  supply. 

This  matter  of  regulating  the  speed  of  pumping  engines,  the 
quantity  of  water  they  pump,  and  the  pressure  in  the  force 
main,  has  been  much  studied  from  time  to  time  by  engineers  and 
pumping  engine  builders.  The  writer  distinctly  remembers 
that  a  good  many  years  ago  he  put  in  a  lot  of  planning  over 
differential  and  compound  levers  acting  against  a  water  plunger 
and  controlled  by  weights,  so  as  to  produce  the  effect  of  a 
spring  but  with  the  use  of  a  weight,  and  so  produce  a  control- 
lable effect  as  with  a  weight  instead  of  an  unknown  increasing 
effect  as  with  the  unknown  and  unknowable  characteristics  of 
a  steel  spring.  But  the  apparatus  was  completed  and  attached 
to  the  original  beam  pumping  engines  put  into  the  then  new 
water-works  at  Terre  Haute,  Ind.  Just  how  it  worked  in  actual 
service  has  passed  from  memory;  and  perhaps  it  better  stay 
there,  wherever  it  is. 

The  regulating  of  a  pumping  engine  at  work  has  several 
features  quite  different  from  the  regulation  of  steam  engines 
generally,  very  much  to  the  surprise  of  steam-engine  builders 
who  thought  that  the  only  way  to  make  a  pumping  engine  was 
to  construct  some  pumps  and  then  attach  them  to  their  steam 
engine,  and  that  would  settle  everything.  With  a  mill  or 
factory  engine,  for  example,  the  aim  is  to  keep  the  speed  uni- 
form while  the  amount  of  power  changes;  but  with  the  pump- 
ing engine,  the  speed  and  power  both  change,  and  the  aim  is 
to  keep  the  water  pressure  constant.  Further,  with  a  pumping 
engine  with  a  fixed  cut-off,  the  simple  fact  of  increasing  the 
speed  by  attempting  to  lower  the  water  pressure  by  drawing 
more  water,  increases  the  power  of  the  machine  by  giving  it  a 


HOLLY  QUADRUPLEX  PUMPING  ENGINE  131 

higher  piston  speed  with  the  same  mean  effective  pressure  in 
the  steam  cylinders,  and  the  only  increase  of  power  needed, 
aside  from  what  the  engine  will  naturally  give  by  automatically 
increasing  its  speed,  is  for  the  friction  of  the  increased  quantity 
of  water  flowing.  For  example,  a  few  years  ago  85  Ibs.  steam 
pressure,  75  Ibs.  water  pressure,  and  5,000,000  gallons  per  day 
would  be  pretty  good  work  to  be  done  by,  say,  an  8,000,000 
gallon  engine  working  upon  direct  service  with  the  necessary 
capacity  for  reserve;  and  to  make  the  illustration  simple,  the 
work  is  supposed  to  be  done  in  one  straight  condensing  cylinder, 
although  the  effect  would  be  the  same  distributed  among  the 
four  cylinders  of  the  quadruplex  engine. 

Steam  pressure  85  Ibs.  per  gauge;  water  load  75  Ibs.  pres- 
sure; engine  making  12  expansions  of  the  steam  and  giving  a 
mean  effective  net  pressure  of  26  Ibs.  on  the  piston;  and  pump- 
ing at  the  rate  of  5,000,000  gallons  per  day  through  1,000  ft. 
of  16-inch  main  before  the  water  gets  to  the  distribution  system. 
The  horsepower  would  be  150  at  a  piston  speed  of  100  ft.  per 
minute.  Now,  supposing  that  the  demand  quickly  increased 
25  per  cent,  making  a  pumpage  rate  of  6,250,000  gallons  per 
day,  then  the  horsepower  would  go  up  to  187.5  by  the  in- 
creased piston  speed  up  to  125  ft.  per  minute  with  the  same 
cut-off  and  pressure;  or,  the  same  indicator  card  with  a  higher 
speed.  But  there  would  be  an  increase  of  2.3  per  cent  in  the 
power  necessary  to  cover  the  friction  in  the  force  main  alone, 
from  the  increased  flow  of  water,  and  this  would  call  for  a  cor- 
responding increase  in  the  mean  effective  pressure  to  a  little 
over  27  Ibs.  To  meet  this  the  ratio  of  expansion  would  have 
to  go  down  to  10,  which  would  require  a  letting  out  of  the  cut- 
off accordingly. 

It  becomes  apparent  at  once  that  the  regular  fly-ball  gover- 
nor and  drop  cut-off  would  not  answer,  because  the  attempt  to 
increase  the  speed  of  the  engine  by  drawing  away  the  water 
would  at  once  result  in  shortening  the  cut-off,  which  would  be 
exactly  the  opposite  of  what  it  wanted.  On  the  other  hand, 
should  the  water  be  checked  in  its  flow,  and  the  pressure  tend 


132  PUMPING  ENGINES 

to  go  higher  in  the  force  main,  the  opposite  effect  would  be  the 
result,  and  the  ratio  of  expansion  would  need  to  increase  and 
the  power  lessen,  just  to  the  extent  of  the  decrease  in  the 
friction  of  the  flow.  With  the  fly-ball  governor  and  drop  cut- 
off, the  attempt  to  check  the  speed  of  the  engine  by  raising  the 
water  pressure  against  it  would  result  in  extending  the  point 
of  cut-off  by  the  corresponding  drop  of  the  governor,  which 
would  again  be  just  the  opposite  of  what  would  be  needed. 

From  this  it  will  be  seen  that  the  regulation  of  a  pumping 
engine  on  direct  service  or  on  any  service,  is  something  more 
of  a  problem  than  regulating  a  mill  engine;  and  it  also  appears 
that  limiting  the  top  speed  is  about  all  that  the  fly-ball  gov- 
ernor can  legitimately  do,  so  far  as  automatic  regulation  is 
concerned  and  independent  of  the  water  pressure. 

Up  to  the  time  that  the  use  of  the  quadruplex  pumping 
engine  was  discontinued  in  1882,  and  was  succeeded  by 
the  Gaskill  horizontal  pumping  engine,  also  built  by  the  Holly 
Manufacturing  Company,  there  had  been  erected  in  water 
works  stations  about  80  of  these  machines,  varying  in  capacity 
from  1,000,000  to  6,000,000  U.  S.  gallons,  and  aggregating  a 
daily  capacity  of  about  300,000,000  gallons,  the  average  size 
being  about  3,500,000  gallons  per  24  hours. 


CHAPTER   XI 
THE   GASKILL   PUMPING  ENGINE 

THE  Gaskill  Pumping  Engine,  which  appeared  in  1882,  was 
designed  by  H.  F.  Gaskill,  the  engineer  and  superintendent 
of  the  Holly  Manufacturing  Company,  at  Lockport,  N.  Y.  Ic 
followed  the  Holly  quadruplex  engine,  and  was  brought  out 
by  that  company  to  provide  a  machine  of  lower  cost  and  as 
being  better  adapted  to  the  growing  demand  for  higher  steam 
economy  and  larger  pumping  units  already  beginning  to  make 
themselves  felt  even  at  that  time. 

The  Gaskill  is  a  horizontal  engine  of  the  Woolf  compound 
principle,  and  in  the  form  in  which  it  is  built  makes  a  distinct 
type  of  pumping  machinery.  It  was  the  first  high  duty  pump- 
ing engine  built  as  a  standard  commercial  machine;  and  while 
giving  a  fairly  high  steam  economy,  is  extremely  compact  and 
convenient.  The  engine  is  shown  in  Fig.  26  in  perspective, 
and  in  Fig.  27  in  section. 

Although  its  general  features  of  design  and  construction 
have  been  retained,  improvements  in  some  of  the  details  have 
been  made  from  time  to  time,  and  it  has  fairly  held  its  own  in 
the  water-works  field  where  the  sharpest  kind  of  competition 
has  always  existed.  The  engine  is  of  the  horizontal,  beam, 
crank  and  fly-wheel,  compound  condensing  type;  and  has  two 
identical  sets  of  steam  cylinders  and  double  acting  plunger 
pumps  connected  to  a  single  main  shaft  with  two  cranks  at 
an  angle  of  90  degrees,  and  one  fly-wheel  located  at  the  middle 
of  the  length  of  the  crank  shaft.  In  fact,  the  machine  is  really 
two  complete  pumping  engines,  which,  with  the  exception  of 
both  using  the  same  crank  shaft,  can  be  operated  separately 
and  apart  from  each  other;  either  straight  condensing  or  com- 


134 


PUMPING  ENGINES 


.a 


HARVEY    F.  GASKILL. 


V'     or  THE 

UNIVERSITY  ) 

OF 


GASKILL  PUMPING  ENGINE  135 

pound  condensing,  and  as  lately  produced,  triple  expansion  as 
shown  in  Fig.  28.  The  two  engines  are  located  close  together 
and  side  by  side,  with  the  center  lines  of  all  steam  cylinders 
and  water  cylinders  parallel.  In  the  compound,  which  is  the 
original  class  and  by  far  the  most  built,  there  are  two  high 
pressure  steam  cylinders,  two  low  pressure  steam  cylinders; 
and  two  water  cylinders  containing  double  acting  plungers. 
The  high  pressure  cylinders  are  mounted  upon  the  low  pressure, 
and  the  ratio  of  the  high  and  low  is  generally  4  to  1  in  area,  or 
2  to  1  in  diameter.  The  two  steam  pistons  of  each  independent 
engine  move  in  opposite  directions,  and  have  their  own  cross 
heads  connected  by  suitable  links  to  opposite  ends  of  a  ver- 
tical rocking  beam.  . 

The  two  water  cylinders  are  located  in  front  of  and  in  ine 
with  the  low  pressure  steam  cylinders,  the  plunger  rods  and 
the  low  pressure  piston  rods  being  keyed  to  the  same  cross 
neaas,  these  cross  heads  being  connected  to  the  lower  ends  of 
the  rocking  beams.  About  two  thirds  of  the  distance  from 
the  low  pressure  steam  cylinders  to  the  water  cylinders  there 
are  located  the  heavy  pedestals  for  supporting  the  center  bear- 
ings of  the  rocking  beams,  and  the  general  construction  is  such 
that  the  engine  is  self-contained  in  having  the  working  strains 
within  the  lines  of  resistance.  The  pump  plungers  are  arranged 
to  work  through  solid  rings,  or  through  stuffing  boxes  as  the 
case  may  be,  according  to  the  character  of  the  water;  these 
rings  or  stuffing  boxes  are  bolted  to  an  inner  rib  within  the 
water  cylinder  usual  in  this  type  of  water  end.  The  water 
valves  are  small  (see  Fig.  29),  and  there  are  many  of  them,  con- 
trolled by  brass  springs,  and  work  upon  brass  seats  screwed 
into  the  horizontal,  flat  valve  decks,  the  suction  deck  immedi- 
ately below  and  the  discharge  deck  immediately  above  the 
plunger  barrel.  The  water  cylinders  were  rather  square  and 
box-like  in  their  original  form,  and  were  thoroughly  and  heavily 
ribbed  on  the  outside  so  as  to  combine  the  greatest  strength 
with  a  good  distribution  of  the  metal;  but  the  later  engines 
have  their  water  cylinders  formed  much  more  on  the  circular 


136 


PUMPING  ENGINES 


GASKILL  PUMPING  ENGINE  137 

idea,   and  are    undoubtedly    considerably  stronger    than    the 
original  shape. 

Above  and  below  the  water  cylinders  proper  are  situated 
the  force  and  suction  chambers,  the  suction  chambers  generally 
being  connected  by  a  cross  pipe  underneath,  and  at  the  middle 
of  the  length  of  the  pump,  by  two  90  degree  bends  of  easy 
radius,  joining  in  a  three-way  casting  from  which  the  main 
suction;  pipe  extends  out  at  the  extreme  water  end  of  the 
machine,  and  so  out  of  the  building  or  into  a  well  within  the 
building  as  the  case  may  be.  In  the  original  engine  the  force 
chambers  were  bolted  on  top  of  the  water  cylinders,  but  in  the 
later  machines  cast  solid  with  the  cylinders;  on. top  of  the  force 
chambers  are  located  the  main  pillow  blocks  for  the  crank 
shaft  bearings,  and  the  shaft  extending  across  the  engine  car- 
ries one  fly-wheel  at  the  middle  of  its  length;  the  cranks  are 
secured  to  the  ends  of  the  shaft  at  90  degrees  from  each  other 
and  in  line  for  connection  with  the  top  end  of  the  rocking  beams. 

In  the  early  engines  there  was  a  bedplate  extending  com- 
pletely under  each  half  of  the  machine,  and  upon  which  the 
various  members  were  mounted;  but  in  the  later  engines  the 
steam  and  water  ends  practically  rest  upon  separate  founda- 
tion piers,  and  are  connected  by  means  of  heavy  cast  iron  frames 
bolted  in  between  the  inboard  ends  of  the  pumps  and  the 
steam  cylinders  so  as  to  hold  them  rigidly  in  place,  and  there 
are  also  cast  iron  girders  extending  from  the  inner  frames  to 
the  main  pillow  blocks.  The  frames  also  contain  the  bearings 
of  the  rocking  beams,  and  the  cross  head  guides. 

The  discharge  openings  are  located  at  the  outer  ends  of  the 
force  chambers,  and  are  connected  across  by  means  of  90  degree 
bends  with  their  outer  ends  swung  downwards  at  an  angle  of 
45  degrees,  until  they  meet  in  a  three-way  casting,  from  the 
lower  opening  of  which  extends  the  delivery  pipe  straight 
down  through  the  floor,  and  thence  carried  to  the  most  suit- 
able point  for  the  delivery  of  the  water. 

The  Woolf  compound  steam  end  of  the  engine  has  steam 
jacketed  cylinders;  the  early  engines  were  fitted  with  poppet 


138 


PUMPING  ENGINES 


induction  valves  on  the  top  of  the  high  pressure  cylinders,  and 
with  gridiron  exhaust  valves  which  also  serve  as  induction 
valves  for  the  low  pressure  cylinder,  the  location  of  the  cylinders 
permitting  of  this  arrangement,  which  was  admirably  carried 
out  in  the  design.  The  low  pressure  exhaust  valves  are  also 
of  the  gridiron  type,  and  by  a  short  exhaust  pipe  sends  the 
steam  directly  into  the  condenser.  The  regulation  of  the 

point  of  cut-off  was  accom- 
plished by  means  of  a  rocking 
shaft  with  very  limited  mo- 
tion controlled  in  its  angular 
position  by  the  pressure  regu- 
lator already  mentioned  in 
connection  with  the  quad- 
ruplex  engine  built  by  the 
same  company.  The  poppet 
valves  are  operated  by  two 
revolving  shafts  extending 
lengthwise  of  the  engine  and 
driven  by  bevel  gears  directly 
from  the  main  or  crank  shaft ; 
the  valve  is  moved  by  a  verti- 
cal stem  extending  upward 
from  the  valve  to  the  end  of 
a  short  beam  pivoted  to  a 
rigid  column  attached  to  the 

Fig.  29.-  Pump  Valve,  of  Ga,kffl  Eagiue.  framing    °f    the    engine>'    the 

free  end  of  the  beam  is  con- 
nected to  a  link  which  extends  downwards  to  one  side  of  the 
strap  of  a  small  eccentric  on  the  longitudinal  shaft  already 
mentioned.  At  the  opposite  side  of  the  strap  is  a  tailpiece  shod 
with  hardened  steel,  and  as  the  shaft  revolves,  the  tailpiece 
coming  in  contact  with  an  arm  on  the  rocking  shaft  also  shod 
with  steel,  is  prevented  from  further  downward  motion;  the 
opposite  side  of  the  eccentric  strap  continues  in  its  travel  and 
so  depresses  the  outer  end  of  the  beam,  raising  the  inner  end 


GASKILL  PUMPING  ENGINE  139 

of  the  beam,  and  opening  the  poppet  valve.  When  the  tailpiece 
is  made  to  slip  off  from  the  rocking  arm  by  the  further  move- 
ment of  the  eccentric,  the  valve  quickly  closes  and  cuts  off  the 
steam.  The  gridiron  valves  are  driven  by  eccentrics  from  the 
same  shaft  that  operates  the  poppet  valves,  one  eccentric 
operating  both  high  and  low  pressure  exhaust  valves. 

The  later  engines  are  fitted  with  the  Corliss  type  of  steam 
valves  and  valve  gear,  operated  by  eccentrics  on  the  main  shaft, 
excepting  that  the  high  pressure  induction  valves,  instead  of 
having  the  detaching  drop  cut-off,  arc  arranged  so  that  the 
closure  is  made  by  positive  means  absolutely  controlled  by  the 
engine.  Fig.  30  and  Fig.  31  show  the  general  construction  of 
the  later  Gaskill  engines,  although  in  some  sizes  the  main 
cross  head  carries  the1  inner  end  of  the  connecting  rod,  and  the 
rocking  beam  is  driven  by  a  pair  of  links  between  which  the 
connecting  rod  passes,  whereas  in  the  figures  here  given  as  in 
the  original  design  the  inner  end  of  the  connecting  rod  is  carried 
by  the  top  end  of  the  rocking  beam. 

There  are  two  air  pumps,  one  for  each  side  of  the  machine, 
driven  from  arms  attached  to  the  center  shafts  of  the  rocking 
beams,  and  are  located  in  the  space  between  the  steam  and 
water  ends.  The  condenser,  generally  of  the  jet  type,  is 
located  below  and  between  the  low  pressure  cylinders,  giving 
short,  easy,  and  quick  passage  for  the  exhaust  steam. 

The  steam  pistons  are  usually  of  the  plain  cast  iron  ring 
variety,  with  internal  springs,  although  sometimes  sectional 
packing  is  used  The  water  plungers  are  hollow  and  closed  at 
the  ends,  with  the  rod  extending  clear  through  the  entire  length 
of  the  plunger,  secured  by  a  stoppered  nut  at  the  outer  end. 
The  plungers  are  arranged  to  work  through  different  forms  of 
rings  according  to  the  water,  sometimes  a  plain  solid  ring,  but 
mostly  through  stuffing  boxes,  as  shown  in  the  sectional  eleva- 
tion. 

The  operation  of  the  engine  is  as  follows : 

Steam  is  admitted  through  the  automatic  cut-off  poppet 
valves  into  the  high  pressure  cylinders,  forcing  the  piston  for- 


140  PUMPING  ENGINES 

ward  under  nearly  full  boiler  pressure  until  the  point  of  cut-off 
is  reached.  The  induction  or  admission  valve  then  suddenly 
closes,  and  the  remaining  portion  of  the  stroke  is  completed  by 
the  expansive  force  of  the  steam.  When  the  high  pressure 
piston  has  nearly  reached  the  end  of  its  travel,  the  gridiron 
slide  valve,  which  acts  as  an  exhaust  for  the  high  pressure  and 
an  induction  valve  for  the  low  pressure,  opens  and  the  steam 
in  the  high  pressure  cylinder  passes  into  the  low  pressure  cylinder 
and  drives  the  low  pressure  piston  the  length  of  its  stroke  in 
the  same  direction  the  high  pressure  has  just  traveled,  the 
steam  expanding  to  four  times  its  volume,  at  the  time  of  the 
high  pressure  exhaust.  The  release  from  the  low  pressure 
cylinder  is  accomplished  by  means  of  the  gridiron  exhaust 
valve  at  the  side  of  the  cylinder;  the  steam,  now  expanded 
down  to  a  very  low  point,  escaping  into  the  condenser  where 
it  is  condensed  again  into  water.  This  operation  is  repeated 
at  every  stroke  of  the  engine  by  each  high  and  low  pressure 
steam  cylinder  alternately;  the  change  from  poppet  and  grid- 
iron valves  to  Corliss  valves  does  not  change  the  principle  of 
the  machine  in  any  particular;  the  cut-off  and  expansion  in 
the  high  pressure,  and  the  full  stroke  expansion  in  the  low 
pressure  remaining  the  same,  as  also  does  the  combined  ex- 
haust and  the  induction  valves  between  the  two  cylinders. 

The  Gaskill  pumping  engine  is  the  only  consistent  attempt 
so  far  made  to  increase  the  economy  of  the  original  Worthing- 
ton  form  of  machine  by  adding  a  crank  and  fly-wheel  to  the 
four  steam  cylinders  and  two  water  cylinders.  There  is  no 
doubt  that  it  was  brought  out  for  this  very  purpose  when  the 
low  duty  non-rotative  machine  with  its  limited  ratio  of  steam 
expansion  was  at  the  zenith  of  its  time,  but,  as  already  pointed 
out,  the  Gaskill  was  soon  followed  by  the  Worthington  high 
duty,  and  this  brought  the  two  rival  establishments  to  nearly 
equal  commercial  terms,  so  nearly  so  in  fact,  that  one  of  them 
a  few  years  later  succeeded  in  swallowing  the  other.  But  the 
non-rotative  engine  lost  the  claim  for  simplicity  of  construction 
so  long  and  so  strongly  put  forward,  and  justly  too  for  so  many 


be 

•I 


w 

I 


bo 

s 


GASKILL  PUMPING  ENGINE  141 

years,  by  the  direct  acting  advocates;  which  all  goes  to  show 
that  low  duty  means  simplicity  of  machinery,  and  high  duty 
means  more  complicated  machinery;  the  main  question  being 
where  to  draw  the  line  so  as  to  balance  the  account  to  a  rea- 
sonable extent.  The  original  type  of  Worthington  low  duty 
engine,  the  high  duty  Worthington,  and  the  original  Gaskill 
engines  have  moving  parts  and  joints  as  follows : 

Worthington  Low  Duty. 

Steam  pistons 4 

Steam  valves 4 

Water  plungers 2 

Stuffing  boxes 14 

Journals 28 

Worthington   High  Duty. 

Steam  pistons 4 

Steam  valves 16 

Water  plungers 2 

Stuffing  boxes 35 

Journals 90 

Original  Gaskill. 

Steam  pistons 4 

Steam  valves 12 

Water  plungers .m 2 

Stuffing  boxes 20 

Journals 100 

The  Gaskill  pumping  engine  completely  supplanted  the 
quadruplex  machine,  and  was  arranged  to  regulate  by  the 
same  means  as  its  predecessor,  the  poppet  valves  as  employed 
in  the  new  machine  lending  themselves  very  readily  to  the  pur- 
pose. This  engine  requires  practically  no  more  room  than  its 
low  duty  rival,  and  in  fact  represents  the  direct  acting  ma- 
chine with  the  high  pressure  cylinder  placed  on  top  of  the  low 
pressure  instead  of  in  front  of  it,  and  this  shortened  up  the 
design  so  that  the  increased  distance  between  the  steam  and 
water  ends  to  accommodate  the  rocking  beams  resulted  in  about 
the  same  total  length  over  all.  The  mounting  of  the  fly-wheel 


142  PUMPING  ENGINES 

above  and  between  the  pumps  only  made  a  slight  increase 
in  the  height  without  increase  in  the  length  of  the  water  end, 
so  that  any  building  large  enough  for  one  gave  sufficient  space 
for  the  other. 

Since  the  introduction  of  the  Gaskill  pumping  engine  in 
1882,  there  have  been  furnished  to  various  cities  and  towns 
about  200  of  these  engines,  with  an  aggregate  pumping  capa- 
city per  24  hours  of  approximately  1,250,000,000  U.  S.  gallons; 
the  smallest  built,  of  1,000,000  and  the  largest  20,000,000 
gallons  daily  capacity;  the  average  capacity  being  about 
6,000,000  gallons. 


CHAPTER   XII 

THE  REYNOLDS  TRIPLE  EXPANSION 
PUMPING  ENGINE 

THE  vertical,  triple  expansion,  crank  and  fly-wheel  condens- 
ing pumping  engine,  which  about  twenty  years  ago,  1886,  devel- 
oped into  a  pronounced  type,  has  since  been  repeated  many 
times,  and  has  been  copied  in  all  essential  features  by  most 
of  the  builders  of  large  sized  pumping  engines  in  the  country. 
It  was  originally  designed  at  the  works  of  the  Edward  P.  Allis 
Company  of  Milwaukee,  Wis.,  by  Irving  H.  Reynolds,  under 
the  supervision  of  Edwin  Reynolds,  the  general  superintendent 
of  the  establishment;  this  triple  expansion  machine,  which  is 
of  6,000,000  U.  S.  gallons  daily  capacity,  being  a  very  natural 
development  of  the  three  crank  compound  pumping  engines 
designed  by  Edwin  Reynolds  for  the  Allegheny,  Pa.,  water 
works  in  1883,  and  who  had  just  previously,  in  1881,  designed 
and  built  his  first  large  pumping  engine  for  the  Milwaukee 
water  works;  this  first  machine  being  a  peculiar  form  of 
beam  engine,  compound  condensing,  with  one  bucket  and 
plunger  pump  directly  beneath  the  steam  cylinders;  and  was 
erected  in  the  North  Point  pumping  station  in  1881.  (See  Fig. 
32  for  a  general  view,  and  Fig.  33  for  a  sectional  elevation.) 
This  form  of  engine  was  never  repeated,  probably  on  account 
of  cost,  although  it  gave  a  little  over  104,000,000  duty  per  100 
Ibs.  of  coal  burned  on  the  grates. 

The  next  step  after  the  Milwaukee  beam  engine  of  1881, 
which  was  of  12,000,000  U.  S.  gallons  capacity,  was  the  com- 
pound condensing  engines  of  6,000,000  gallons  capacity,  two 
of  which  were  built  and  installed  for  Allegheny,  Pa.,  in  1883 
and  1884,  where  they  were  tested  by  Professor  David  M. 

143 


144 


PUMPING  ENGINES 


\ 


Fig.  32.— Eeynolds  Beam  Pumping  Engine,  Milwaukee. 


EDWIN    REYNOLDS. 


OF  THE 


REYNOLDS   TRIPLE  EXPANSION  PUMPING  ENGINE    145 

Green  and  the  writer  in  the  latter  year;  the  duty  obtained  was 
107,000,000  ft.  Ibs.  per  1,000  Ibs.  of  steam,  or,  as  it  was  then 
put,  per  100  Ibs.  of  coal  based  upon  an  evaporation  in  the 
boilers  of  10  to  1. 

In  the  Allegheny  engines  the  departure  was  radically  made 


Fig.  33.  —  Sectional  View  of  Reynolds  Beam  Pumping  Engine. 

from  four  displacements  per  revolutions,  which  had  been  the 
usual  delivery  method,  to  three  displacements  with  the  cranks 
at  angles  of  120  degrees  around  the  circle;  and  it  immediately 
cut  down  the  number  of  steam  cylinders  from  four,  as  in  the 


146 


PUMPING  ENGINES 


Fig,  34. — Eeynolds  Three  Cylinder  Compound  Pumuing  Engine. 


I 
REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE  147 

Worthington  and  Gaskill  engines,  to  three,  and  produced  a 
practicable  high  type  of  pumping  engine  of  great  simplicity. 
See  Fig.  34  and  Fig.  35  for  front  and  side 'elevations,  sections, 
etc.,  showing  one  high  pressure  steam  cylinder  and  two  low 
pressure  cylinders,  with  three  single  acting,  outside  packed 
plunger  pumps.  These  engines  were  two  in  number,  exactly 
alike,  both  in  general  arrangements  and  in  detail,  of  the  verti- 
cal, three  cylinder,  compound  rotative  type,  with  large  re- 
ceivers between  the  high  and  low  pressure  cylinders.  Each 
steam  piston  operated  a  single  acting  solid  plunger  pump, 
placed  in  a  pit  vertically  underneath  each  steam  cylinder. 
The  center  lines  of  the  three  steam  cylinders  and  the  three 
pumps  are  all  in  the  same  vertical  plane  in  which  above  the 
steam  cylinders  is  located  the  main  crank  shaft  in  two  pieces, 
which  carry  two  fly-wheels  weighing  about  10  tons  each,  one 
wheel  over  each  of  the  two  spaces  between  the  three  cylinders. 
The  wheels  are  placed  overhead,  the  crank  shafts  mounted  in 
pillow  blocks  at  the  top  of  the  A  frames,  secured  to  the  main 
bedplates,  the  bedplates  resting  upon  the  foundations,  and  the 
steam  cylinders  secured  to  the  bedplates  between  the  A  frames. 

The  valve  gear  is  of  the  Corliss  type  with  details  designed 
by  Edwin  Reynolds,  adjustable  by  hand  on  the  two  low  pres- 
sure cylinders,  while  that  of  the  high  pressure  is  very  effectually 
regulated  by  the  ordinary  fly-ball  governor,  the  machinery 
being  always  operated  at  full  speed  capacity.  The  receiver 
is  cylindrical,  horizontal,  and  mounted  behind  the  steam  cylin- 
ders at  about  the  level  of  the  cylinder  tops.  The  cylinders 
are  steam  jacketed,  packed  around  their  outside  barrels  with 
mineral  wool,  and  lagged  with  black  walnut;  the  receiver  is 
also  covered  with  non-conducting  material  and  lagged  to.  cor- 
respond with  the  steam  cylinders.  The  water  of  condensa- 
tion from  the  steam  jackets  and  receiver  was  discharged  through 
traps  operating  automatically,  and  the  receiver  has  no  reheat- 
ing coils. 

The  pump  valves  were  originally  of  the  Cornish  double  beat 
type,  of  brass;  there  were  seven  suction  and  seven  discharge 


148 


PUMPING  ENGINES 


Fig.  35. — Reynolds  Three  Cylinder  Compound  Pumping  Engine. 


REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    149 

valves  for  each  plunger,  and  right  here  comes  in  an  illustra- 
tion of  how  satisfactory  permanent  results  are  sometimes  ob- 
tained in  trying  to  escape  from  a  difficulty  which  has  presented 
itself.  The  waters  of  the  Allegheny  River  contained  sufficient 
troublesome  floating  refuse  to  interfere  with  the  proper  opera- 
tion of  the  brass  Cornish  pump  valves,  when  such  refuse  came 
between  a  hard  non-elastic  seat  and  valve,  which  of  course  a 
brass  valve  and  seat  would  be.  The  writer,  who  was  then  in 
the  employ  of  the  Allis  Company,  watched  the  operation  of 
the  pumps  and  reported  from  time  to  time,  until  it  was  evident 
that  the  hard  unyielding  pump  valves  seating  themselves 
upon  equally  hard  brass  seats,  were  decidedly  objectionable 
under  Allegheny  River  conditions.  But  there  were  the  main 
pump  chambers,  representing  a  good  deal  of  cost  and  perma- 
nently set  in  place  in  the  pump  pit.  Each  valve  deck  with 
seven  holes,  each  8  inches  in  diameter  through  it,  entirely  un- 
fitted for  the  application  of  rubber  valves  in  the  usual  way; 
and  in  fact  totally  unable  to  furnish  the  proper  valve  area  as 
generally  applied.  The  remedy  employed  resulted  in  a  form 
of  cage  construction  shown  in  Fig.  36  and  Fig.  37;  these  cages 
held  hi  place  by  one  large  center  bolt  which  took  the  place  of 
the  central  bolt  of  the  Cornish  valve.  This  overcame  the 
difficulty  completely  and  conclusively,  and  in  fact  so  well  that 
it  was  adopted  as  a  permanent  detail  of  the  Reynolds  pump- 
ing engines  and  is  used  even  to-day  in  the  construction  of  this 
type  of  machinery.  The  illustrations  given  in  the  figures  of 
this  engine  are  from  an  old  engraving,  and  the  dome-like  form 
of  the  old  Cornish  valves  may  be  plainly  seen  in  the  picture, 
especially  with  the  aid  of  a  magnifying  glass  to  enlarge  the 
detail. 

The  next  Reynolds  pumping  engine  was  a  vertical  two 
plunger  compound  condensing  machine,  having  outside  packed 
plungers,  which  type  of  plunger  has  always  been  favored  by 
the  designer  of  these  engines.  The  general  design  of  this  two 
plunger  engine,  or  as  much  of  it  as  shows  above  the  engine 
room  floor,  appears  in  Fig.  38  and  is  of  the  "see-saw"  class, 


150 


PUMPING  ENGINES 


where  two  plungers  have  directly  opposite  movements  at  the 
same  time,  making  a  good  enough  delivery,  perhaps,  for  reser- 
voir work  with  a  direct  force  main,  but  very  objectionable 
where  consumers  of  water  are  attached  to  the  main,  or  distrib- 


Fig.  36.  —  Cage  Construction  of  Pump  Valve  Seats. 

uting  pipes  leading  from  a  main  connected  with  this  type  of 
two  plunger  machine.  As  an  example  of  the  possible  and 
probable  annoyance  to  consumers  arising  from  the  use  of 
two  plunger  "see-saw"  pumping  engines,  the  writer  recalls 
an  extended  examination  into  the  matter  in  Milwaukee,  and 


REYNOLDS   TRIPLE  EXPANSION  PUMPING  ENGINE    151 

could  count  every  stroke  of  the  pumps  at  the  kitchen  faucets 
of  every  house  within  the  high  service  district  supplied  by 
one  of  these  engines. 

Pumping  engines  of  this  vertical  two  plunger  compound  con- 
densing type,  were  designed  and  built  for  Milwaukee,  St.  Paul, 
and  some  other  cities,  and  the  final  one  for  Hannibal,  Mo., 
mention  of  which  has  already  been  made.  In  the  latter  engine 


Fig.  37.  —  Cage  Construction  of  Pomp  Valve  Seats. 

some  of  the  important  features  seen  in  the  later  triple  expansion 
design  first  appeared;  such  as  closer  clearance  and  smaller 
waste  room  at  the  steam  cylinder  ends,  especially  in  the  low 
pressure,  the  last  cylinder  to  receive  the  steam  before  it  is 
lost  in  the  condenser.  This  is  the  first  pumping  engine  of  the 
Corliss  type  steam  end  with  the  valves  across  the  cylinder 
heads,  with  the  single  exception  of  the  Pawtucket  engine  de- 
signed and  built  by  Geo.  H.  Corliss  in  1877,  although  this 


152 


PUMPING  ENGINES 


X^ 

/  OF  THE 

|    UNIVERSITY   ] 

OF 


REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    153 

location  of  steam  valves  was  not  new  even  at  that  time,  as  the 
Corliss  Centennial  power  engine  at  Philadelphia  in  1876  was  so 
provided.  This  detail  in  engine  design  is  an  extremely  im- 
portant one  where  high  steam  economy  is  sought,  because  the 
less  the  waste  room  which  has  to  be  filled  with  steam  at  the 
cylinder  ends  at  each  stroke,  the  nearer  the  approach  to  theo- 
retical cylinder  displacement.  And  the  advantage  of  the 
cross-the-head  form  of  valves  is  that  they  avoid  the  corners 
at  the  ends  of  the  steam  and  exhaust  ports  formed  by  the  dif- 
ference between  the  straight  line  of  the  valve  seat  and  the  cir- 
cular line  of  the  cylinder  bore.  The  introduction  of  poppet 
valves  into  this  type  of  pumping  engine  has  still  further  reduced 
the  waste  room,  and  brought  it  down  to  merely  the  necessary 
clearance  for  the  piston  and  head,  the  matter  of  port  room 
having  been  entirely  wiped  out  of  the  case  with  the  poppet 
form  of  admission  and  exhaust  valves. 

Immediately  after  the  Hannibal  engine  had  given  a  duty  of 
118,000,000  ft.  Ibs.  per  1,000  Ibs.  of  steam,  the  writer  made  a 
duty  test  of  the  same  type  at  the  high  service  pumping  station 
of  the  Milwaukee  water  works  on  Grand  Avenue,  but  the  latter 
engine  had  the  old-fashioned  cylinders  with  the  valves  at  the 
corners,  and  failed  to  reach  95,000,000  ft.  Ibs.  duty  per  100  Ibs. 
of  coal  burned,  but  making  99,000,000  duty  per  1,000  Ibs.  of 
steam.  About  a  month  later  a  test  of  a  similar  engine  at  the 
St.  Paul  water  works  of  fairly  good  size,  demonstrated  beyond 
all  doubt  in  the  light  of  the  Hannibal  experience  that  the  small 
clearance,  the  only  difference  in  these  engines,  was  the  key  to 
a  good  deal  of  improvement  hi  steam  economy,  and  as  it  cost 
no  more  to  build  the  engines  this  way,  of  course  it  was  the 
proper  line  to  follow. 

After  further  discussion  regarding  the  Milwaukee  compound 
engine,  which  was  not  up  to  contract  duty  requirements,  the 
suggestion  naturally  enough  came  about  of  its  replacement  by 
the  then  new  idea  of  a  triple  expansion  machine,  with  the 
steam  cylinders  fitted  with  the  valves  across  the  heads;  and  so 
the  agreement  upon  the  new  type,  really  the  joint  efforts  of 


154 


PUMPING  ENGINES 


Fig,  39. — Beynolds  Triple  Expansion  Pumping  Engine. 


REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    155 

three  people,  was  arranged  with  the  city.  This  is  the  first 
triple  expansion  pumping  engine  in  the  world's  record,  and  it 
proved  an  immediate  success.  A  general  view  of  this  machine 
is  given  in  Fig.  39,  and  it  will  be  observed  that  it  looks  very 
much  like  the  latest  productions  of  this  type,  the  principal 
features  being  unchanged  at  the  present  time,  although  some 
refinements  in  the  smaller  details  have  been  carried  out.  The 
duty  of  this  newcomer  in  1886  ran  up  to  about  122,452,724  ft. 
Ibs.  per  100  Ibs.  of  coal,  with  return  tubular  boilers  carrying 
80  Ibs.  gauge  steam  pressure;  and  its  successors  from  the  same 
establishment  have  ever  since  held  the  high  duty  record,  the 
present  figures  reaching  in  April,  1906,  a  little  upward  of 
181,000,000,  which  from  all  evidence,  investigation,  and  proba- 
bilities, is  very  close  to  the  limit  of  the  accomplishment  in  the 
high  duty  line  of  effort,  with  the  use  of  dry  saturated  steam, 
and  for  1,000  Ibs.  consumed,  including  jackets  and  reheaters 
in  the  receivers. 

This  original  triple,  of  1886,  has  the  following  dimensions: 

High  pressure  cylinder,  21  inches  diameter. 

Intermediate  cylinder,    36  inches  diameter. 

Low  pressure  cylinder,   51  inches  diameter. 

Pump  plungers,  three  single  acting,  23^  inches  diameter. 

Stroke  of  all,  36  inches. 

The  steam  pressure  specified  by  the  city  was  not  to  exceed 
80  Ibs.  per  gauge,  and  this  rather  low  pressure  was  stipulated 
because  of  the  boilers  already  in  the  station  and  which  the 
city  did  not  desire  to  replace  at  that  time.  The  total  load 
on  the  plungers  was  about  48  Ibs.  to  the  square  inch,  and  the 
capacity  of  the  engine  was  6,000,000  gallons  per  24  hours. 
There  were  plenty  of  predictions  made  that  with  the  low 
steam  pressure  of  80  Ibs.,  the  triple  expansion  idea  would  prove 
unsuccessful  so  far  as  economy  of  its  steam  wras  concerned; 
but  there  are  records  of  duty  of  129,000,000  per  1,000  Ibs.  of 
steam  from  this  engine,  which  calls  for  a  little  less  than  9J  Ibs. 
evaporation,  a  very  reasonable  figure  with  the  clean  anthracite 


156 


PUMPING  ENGINES 


Fig.  40.  — North  Point,  Milwaukee,  Triple  Pumping  Engine. 


REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    157 

coal  used,  the  boilers  in  good  order,  and  with  the  moderate 
steam  pressure  to  evaporate  the  water  against;  that  is  to  say, 
a  coal  duty  of  122,452,724  and  a  1,000  Ibs.  of  steam  duty  of 
129,000,000  call  for  9i  Ibs.  evaporation  in  the  boilers  under  80 
Ibs.  gauge  steam  pressure. 

These  results  bear  out  the  idea  held  for  years  by  the  writer, 
that  if  the  gain  from  multiple  expansion  is  due  to  a  considerable 
reduction  in  the  range  of  temperature  within  the  cylinders, 
then  the  benefit  should  show  with  moderate  pressures  as  well 
as  with  high  pressures.  Of  course  the  higher  pressure  of  initial 
steam,  with  the  same  terminal  pressure,  will  give  a  greater 
economy;  but  even  at  that,  the  steam  must  be  protected  by 
reducing  the  range  of  temperature,  and  as  4  or  5  expansions 
is  about  the  limit  in  one  cylinder,  there  should  be  and  is  a  very 
considerable  improvement  in  steam  economy  in  tripling,  even 
with  80  Ibs.  pressure  of  steam.  At  all  events,  the  steam  pressure 
has  been  more  than  doubled  in  20  years,  and  the  duty  only 
increased  40  per  cent  clear  up  to  the  new  record  of  181,000,000 
now  held  at  St.  Louis,  Mo.,  by  a  successor  of  the  original  triple 
engine  from  the  Milwaukee  concern. 

This  form  of  construction  of  the  Reynolds  pumping  engine 
marked  and  identified  this  type,  which  made  another  decided 
record  stride  forward  in  the  large  North  Point  engine  with  a 
24  hour  capacity  of  18,000,000  U.  S.  gallons,  at  the  main  station 
of  the  Milwaukee  water  works  in  1892,  with  a  duty  of  154,048,704 
ft.  Ibs.  per  1,000  Ibs.  of  dry  steam.  (See  Fig.  40.) 

Still  another  step  forward  was  taken  with  Engine  No.  10  in 
the  St.  Louis  water  works  in  1900  with  a  24  hour  capacity  of 
15,000,000  U.  S.  gallons,  which  developed  a  duty  of  179,454,250 
ft.  Ibs.  per  1,000  Ibs.  of  dry  steam.  The  record  has  again  been 
broken,  in  April,  1906,  also  at  St.  Louis,  with  one  of  the  same 
type  and  make  of  machinery,  when  a  duty  of  181,068,605  ft. 
Ibs.  per  1,000  Ibs.  of  dry  steam  was  obtained. 

This  type  of  pumping  engine,  the  general  appearance  of  which  is 
given  in  Fig.  41,  as  its  steam  or  power  end  appears  above  and  be- 
low the  floor  of  the  engine  room,  is  really  three  separate  vertical 


158  PUMPING  ENGINES 

steam  engines  set  side  by  side.  Each  is  upon  its  own  bed- 
plate and  with  its  own  framing ;  the  first  or  high  pressure  cylin- 
der takes  its  steam  directly  from  the  boiler,  and  as  nearly  to 
boiler  pressure  as  it  is  possible  and  practicable  to  get  it,  and 
exhausts  into  a  receiver  which  acts  as  a  sort  of  boiler  for  the 
second  or  intermediate  cylinder;  this  second  or  intermediate 
cylinder  taking  its  steam  from  this  first  receiver  and  exhaust- 
ing it  into  a  second  receiver  which  answers  for  the  boiler  for  the 
third,  last,  or  low  pressure  cylinder ;  and  the  third  or  low  press- 
ure cylinder  taking  its  steam  from  the  second  receiver  exhausts 
into  the  condenser.  The  idea  is  to  keep  the  pressure  in  the  two 
receivers  exactly  at  the  terminal  pressure  of  the  cylinder  from 
which  the  steam  comes,  so  that  there  will  be  no  drop  of  pressure 
when  the  exhaust  takes  place,  the  receiver  being  made  large 
enough  to  prevent  any  appreciable  change  in  its  pressure  from 
the  incoming  and  outgoing  steam.  -  The  result  of  this  operation 
is  to  get  the  benefit  in  work  of  all  of  the  expansion,  and  to 
allow  no  expansion  to  take  place  without  a  corresponding  effect 
upon  the  pistons  of  the  three  cylinders.  It  is  just  the  same 
as  making  one  large  indicator  card  in  one  cylinder,  and  then 
cutting  it  by  horizontal  lines  into  three  parts,  which  give  equal 
power  in  each  diagram.  This  is  not  exactly  and  precisely  done 
in  practice,  but  it  is  approached  very  closely,  and  it  is  the 
method  for  comparing  the  effectiveness  of  the  steam  distri- 
bution. 

The  exhaust  steam  from  the  high  and  intermediate  pressure 
cylinders  is  "reheated"  by  means  of  steam  circulating  in  coils 
within  the  bodies  of  the  receivers;  and  the  cylinders  are  jacketed 
by  steam,  both  at  the  sides  and  heads,  in  the  most  effective 
engines.  One  of  the  most  efficient  arrangements  of  steam 
jacket  and  receiver  heating  pipes,  perhaps  as  good  as  any,  is 
as  follows: 

Boiler  pressure,  or  as  nearly  as  may  be,  from  the  main  steam 
pipe  near  the  engine,  passes  to  the  top  of  the  high  pressure 
jacket,  and  out  at  the  bottom  of  the  jacket.  Then  through 
a  branch  in  the  high  pressure  jacket  outlet  to  a  Flynn  trap, 


Fig.  41. — Beynolds  Self-Coutained  Triple  Pumping  Engine. 


REYNOLDS   TRIPLE  EXPANSION  PUMPING  ENGINE    159 

and  from  the  discharge  of  this  trap  to  the  top  of  the  low  pres- 
sure cylinder  jacket.  Another  branch  from  the  high  pressure 
jacket  outlet  goes  to  the  coil  in  the  first  receiver  at  the 
top;  then  out  of  the  bottom  end  of  this  first  receiver  coil  and 
continues  to  the  top  of  the  intermediate  pressure  jacket,  then 
from  the  bottom  of  the  intermediate  jacket  to  the  top  of  the 
low  pressure  jacket.  The  steam  between  the  high  pressure 
jacket  and  the  first  receiver  coil  is  throttled  so  as  to  reduce  the 
pressure  in  the  latter,  the  natural  condensation  for  the  high 
pressure  jacket  going  through  the  Flynn  trap  already  men- 
tioned, to  the  low  pressure  cylinder  jacket.  The  condensation 
from  the  working  steam  in  the  first  receiver  goes  to  the  top  of 
the  coil  in  the  second  receiver,  and  from  the  bottom  of  the 
second  receiver  coil  to  the  top  of  the  low  pressure  jacket.  No 
reducing  valves  are  used,  but  the  pressure  from  high  to  low  is 
regulated  by  two  globe  valves  in  the  pipe,  one  valve  directly 
after  the  other.  The  final  outlet  from  the  low  pressure  jacket 
at  the  bottom  goes  to  a  water  seal  in  the  basement  of  the  build- 
ing, the  pressure  being  so  low  that  no  steam  trap  is  required. 

High  pressure  jacket  has  boiler  pressure. 

Intermediate  jacket  has  40  Ibs.  steam  pressure. 

Low  pressure  jacket  has  0  on  the  ordinary  steam  gauge. 

The  water  end  of  the  Reynolds  engine  consists  of  three  pumps, 
one  of  the  pumps  below  and  in  line  with  each  steam  cylinder. 
The  main  framing  is  very  heavy  in  comparison  to  the  work  to 
be  done  by  the  engine  and,  although  apparently  massive,  is 
in  good  proportion;  but  of  course  beyond  a  reasonable  calcu- 
lation as  to  factors  of  safety  the  real  needed  strength  of  machine 
framing  is  not  known  excepting  by  experience.  The  designer 
of  this  machinery  was  once  asked  by  a  party  inspecting  one  of 
these  engines  if  the  framing  was  not  too  strong,  and  the  reply 
was  "  If  it  is  too  strong  nobody  knows  it,  but  if  it  were  too  weak 
everybody  would  know  it." 

In  some  forms  of  the  engine  the  framing  is  shaped  like  a 
double  letter  A,  while  in  late  machines  what  is  known  as  a 


160  PUMPING  ENGINES 

single  A  frame  is  used.  At  the  top  of  the  A  frames  are  placed 
the  steam  cylinders,  and  the  bottom  or  feet  of  the  framing  rest 
upon  and  are  securely  bolted  to  the  main  bedplates  in  which 
are  located  the  main  pillow  blocks.  There  are  four  pillow 
blocks,  one  at  the  inner  edge  of  the  high  and  the  low  pressure 
bedplates,  and  two  on  the  intermediate  bedplate.  These  four 
pillow  blocks  support  two  main  or  crank  shafts  which  carry 
the  fly  wheels,  the  wheels,  two  in  number,  swinging  in  the  two 
spaces  formed  by  the  three  bedplates.  The  fly  wheels  are 
rather  heavy,  sometimes  weighing  in  the  larger  engines  as  high 
as  30  tons  each.  These  wheels  may  seem  heavy,  but  the  dan- 
gerous effects  of  fly  wheels  on  water  columns  and  force  mains 
has  been  very  much  overstated  by  advocates  of  the  non-rota- 
tive forms  of  pumping  engines.  The  fact  is  that,  with  the  low 
rate  of  revolution  of  a  proper  crank  and  fly  wheel  pumping 
engine,  the  drag  produced  by  such  a  stubborn  load  as  water 
largely  dominates  and  controls  the  machine,  and  the  writer 
was  enabled  several  years  ago  to  try  some  experiments  upon 
this  point  which  clearly  illustrates  how  little  real  effect  the  fly 
wheel  exerts  beyond  the  regulation  of  the  motion  of  the 
engine  with  reference  to  the  cutting  off  and  expansion  of  the 
steam. 

The  case  was  as  follows :  a  new  pumping  engine  of  this  type 
and  of  large  size  had  been  started  but  a  short  time,  had  been 
running  a  very  few  days,  and  naturally  was  not  yet  in  perfect 
adjustment.  Occasionally  it  was  observed  to  come  very  quietly 
to  a  complete  stop,  and  after  considerable  investigation  it  was 
noted  that  one  of  the  cut-off  hooks  did  not  always  get  hold  of 
the  steam  arm  catch,  on  account  of  the  dash  pot  rod  being 
too  short  and  the  catch  going  down  too  far  now  and  again. 
The  length  of  the  rod  was  properly  adjusted  and  then  all  went 
well,  but  the  suggestion  arose  to  slip  a  thin  wooden  wedge 
between  the  hook  and  catch  after  full  speed  had  been  reached 
by  the  engine,  to  see  the  effect  on  the  machine  and  what  the 
fly  wheels  would  do  in  the  way  of  carrying  the  engine  along 
against  the  water  column,  the  working  head  being  about  220  ft. 


REYNOLDS   TRIPLE  EXPANSION  PUMPING  ENGINE    161 

The  result  was  rather  surprising,  for  even  with  a  three  cylinder 
engine  having  cranks  at  three  points  on  the  circle  120  degrees 
apart,  taking  steam  six  tunes  per  revolution,  there  was  not 
enough  momentum  in  the  fly  wheels  and  moving  parts  to 
carry  the  engine  one  revolution  and  have  the  single  cut-off 
hook  operate  after  having  been  interfered  with  for  a  single 
stroke. 

As  already  mentioned,  there  are  two  shafts  in  the  Reynolds 
pumping  engine,  extending  from  high  pressure  and  from  low 
pressure  bedplates  to  the  intermediate  bedplate,  and  at  each 
end  of  each  shaft  is  secured  a  crank,  the  two  middle  cranks 
coming  nearly  together  below  the  intermediate  cylinder,  being 
considerably  larger  and  stronger  than  the  outer  cranks  below 
the  high  and  low  pressure  cylinders.  The  connecting  rods 
extending  from  the  cross  heads  to  the  crank  pins  are  of  liberal 
length,  and,  as  the  cranks  are  set  at  120  degrees  from  each 
other,  the  motion  of  each  pump  plunger  is  controlled  by  its 
own  crank,  and  so  the  plungers  acting  in  conjunction  produce  an 
extremely  even  and  satisfactory  flow  of  water.  The  pumps 
being  single  acting  deliver  water  only  on  the  downward  stroke, 
but  the  plungers  are  weighted  to  half  the  difference  between 
the  suction  and  delivery  loads  so  that  the  steam  cylinders  have 
equal  work  on  both  upward  and  downward  strokes,  and  the 
only  work  going  through  the  crank  shafts  is  that  which  is  given 
to  and  given  back  by  the  fly  wheels  on  account  of  the  expand- 
ing steam. 

The  main  pumps,  three  in  number,  are  of  the  single  acting, 
outside  packed  plunger  pattern,  secured  beneath  the  bedplates 
directly  in  line  with  the  steam  cylinders  so  that  the  force  and 
resistance  of  the  pumping  are  in  the  same  center  line,  thus 
making  the  machine  self  containing  with  reference  to  the  work 
it  is  doing.  The  pump  barrels  proper,  or  the  plunger  barrels 
as  they  might  be  called,  are  separate  castings  from  the  valve 
chambers,  and  this  is  the  better  form  of  construction  for  this 
type  of  water  end;  the  valve  chambers  are  placed  in  front  of 
the  plunger  barrels  and  made  to  form  a  part  of  the  supports 


162 


PUMPING  ENGINES 


Fig    42. — Air  Chambers  Supporting  one  end  of  Bed  Plates. 


REYNOLDS  TRIPLE  EXPANSION  PUMPING  ENGINE    163 

for  the  bedplates  (see  Fig.  42).  The  connections  between  the 
plunger  barrels  and  the  valve  chambers  are  located  so  that  the 
formation  of  air  pockets  is  impossible,  which  is  an  extremely 
important  detail  not  always  appreciated  by  designers  of  pump- 
ing machinery,  even  some  of  those  considered  pretty  good 
ones  as  the  world  goes.  The  course  of  the  water  should  al- 
ways be  upward  and  outward  without  interference,  after  it 
once  gets  inside  of  the  suction  chamber  at  the  bottom  of  the 
pump,  and  overdraughts  and  chances  for  forming  air  bubbles 
and  air  pockets  should  be  avoided. 

The  pump  work  is  all  of  the  cylindrical  form  giving  great 
strength  and  rigidity  in  proportion  to  the  metal  employed. 
The  valve  decks  are  plain  flat  surfaces  well  ribbed  and  sup- 
ported from  underneath,  and  the  pump  valves  are  mounted 
on  cages  as  already  pointed  out  in  Fig.  36  and  Fig.  37.  These 
valves  are  rubber  disks  3J  inches  in  diameter  and  about  one- 
half  inch  thick;  they  work  on  brass  valve  seats  and  are  con- 
trolled by  brass  springs;  the  area  of  each  set  of  valves,  suction, 
and  delivery,  generally  being  about  equal  to  the  area  of  the 
cross  section  of  the  plunger.  Each  pump  has  an  air  chamber 
formed  of  the  upper  portion  of  its  valve  chamber  construction, 
which  supports  the  bedplates;  and  in  some  cases  large  equal- 
izing pipes  connect  the  tops  of  the  air  chambers  thus  formed. 

The  steam  engine  proper,  or  the  steam  power  end  of  the 
machine,  is  practically  a  regular  vertical  triple  expansion  marine 
type  of  engine,  with  cranks,  fly  wheels,  guides,  and  connecting 
rods;  running  at  a  low  speed  to  accommodate  the  pumping  of 
the  water  which  experience  teaches  and  shows  cannot  be  profit- 
ably handled  at  high  speed;  none  of  the  experienced  and  success- 
ful builders  and  users  of  pumping  machinery  being  advocates 
of  high  piston  or  plunger  speeds  for  water  works  engines.  The 
air  pump  for  the  condensing  apparatus  is  driven  sometimes  by 
an  arm  attached  to  the  top  end  of  the  main  plunger  at  the  low 
pressure  end  of  the  engine,  and  sometimes  by  a  rocker  beam 
operated  by  link  connections  from  the  plunger  head;  the  air 
pump  driving  mechanism  also  drives  the  boiler  feed  pump, 


164  PUMPING  ENGINES 

jacket  water  pump,  small  air  compressor  pump,  etc.,  so  that 
there  are  no  auxiliary  apparatus  to  be  driven  by  steam  from 
the  boilers. 

The  connections  between  the  steam  pistons  and  the  water 
plungers  are  by  means  of  the  usual  piston  rods,  from  pistons 
to  main  cross  heads,  sometimes  two  rods  and  sometimes  one 
rod  to  each  piston;  and  then  from  the  main  cross  head  there 
extend  four  heavy  tie  rods  to  the  pump  plunger,  thus  trans- 
mitting the  motion  of  the  piston  directly  to  the  plunger  without 
the  intervention  of  links,  beams,  or  similar  details,  and  making 
the  machine  direct  acting  in  all  essential  effects,  the  mechanical 
efficiency  of  the  larger  machines  going  as  high  as  96  per  cent 
in  some  cases.  The  steam  piston  packing  is  usually  composed 
of  cast  iron  rings  joined  where  the  ends  of  the  rings  come  to- 
gether by  a  brass  "keeper,"  often  two  rings  in  each  piston, 
nearly  square  in  the  section  of  the  ring,  and  backed  by  light, 
thin,  steel  springs  of  just  sufficient  tension  to  hold  the  rings 
against  the  cylinder  walls. 

The  steam  valve  gear  is  of  the  Corliss  type  on  the  high  pres- 
sure and  intermediate  cylinders;  and  on  the  low  pressure  cylin- 
der sometimes  a  combination  of  Corliss  steam  valves  and  poppet 
exhaust  valves  is  used,  while  in  some  of  the  engines  all  poppet 
valves  are  used  on  the  low  pressure  cylinder;  and  sometimes 
the  intermediate  cylinder  is  fitted  with  Corliss  steam  valves 
and  poppet  exhaust  valves.  The  clearance  or  waste  room  in 
these  cylinders  is  often  brought  as  low  as  1J  per  cent  in  the 
high  pressure,  1  per  cent  in  the  intermediate,  and  less  than 
one-half  per  cent  in  the  low  pressure.  The  high  pressure  cut- 
off is  controlled  by  the  usual  fly-ball  governor  for  the  top  speed 
limit,  combined  with  a  variable  hand  adjustment.  The  inter- 
mediate and  low  pressure  cut-offs  are  adjusted  by  hand  and 
set  where  the  operation  of  the  engine  indicates  the  best  effi- 
ciency in  actual  service.  These  engines  have  seldom  been,  if 
ever,  used  on  the  direct  or  closed  system  of  pipes,  and  at  the 
worst  upon  rather  large  systems  or  upon  systems  having  a 
stand  pipe,  and  for  the  reason  that  they  have  generally  been 


REYNOLDS   TRIPLE  EXPANSION  PUMPING  ENGINE    163 

built  of  the  larger  capacities,  because  it  is  doubtful  economy  to 
produce  and  use  triple  expansion  high  duty  engines  upon  a 
small  scale;  but  of  course  the  larger  capacities  mean  extensive 
distribution  systems  even  where  there  are  no  reservoirs,  and 
large  systems  mean  a  very  considerable  percentage  of  the 
pumping  capacity  of  each  engine  utilized,  which  in  turn  means 
a  pretty  free  delivery  and  ease  of  pumping.  Therefore,  beyond 
taking  care  of  the  top  speed  limit,  and  affording  reasonable 
adjustment  where  the  natural  and  automatic  demand  and  sup- 
ply do  not  properly  respond  to  each  other,  there  have  been  no 
practical  attempts  made  at  close  pressure  regulation;  but  qf 
course  there  is  no  reason  whatever  why  a  pressure  regulator 
cannot  be  applied  to  the  vertical  triple  as  well  as  to  other  forms 
of  pumping  machinery. 

Since  the  design  and  introduction  of  the  vertical  triple  expan- 
sion, crank,  and  fly  wheel  pumping  engine  in  1886,  the  original 
builders  have  produced  about  fifty  engines  having  an  aggregate 
capacity  per  24  hours  of  600,000,000  U.  S.  gallons,  other  build- 
ers having  followed  this  design  more  or  less,  having  quickly 
recognized  its  good  qualities,  especially  its  excellent  fitness  for 
use  in  large  sizes,  say  from  10,000,000  to  50,000,000  gallons 
daily  capacity.  Aside  from  the  original  builders  there  have 
been  produced  and  placed  in  water  works  about  thirty  of  these 
engines  by  other  builders  in  different  parts  of  the  country,  and 
it  bids  fair  to  hold  a  very  prominent  place  for  a  long  time  to 
come,  as  there  are  no  signs  at  the  present  time  of  any  great 
advances  in  any  other  direction  in  the  line  of  economically 
pumping  water  for  public  supply. 


CHAPTER   XIII 
VARIOUS  TYPES  AND  CLASSES 

A  REASONABLY  complete  list  of  pumping  engines  which  have 
been  or  now  are  regularly  built  for  water  works,  including  the 
four  pronounced  types  referred  to  in  the  last  chapter,  would 
be  as  follows: 

Non-Rotative  or  Worthington  Direct  Acting  Type 

Compound  non-condensing,  horizontal. 

Compound    condensing,    low   duty,    horizontal.     (Original 

Worthington.) 

Triple  non-condensing,  horizontal. 
Triple  condensing,  horizontal. 
Compound  condensing,  high  duty,  horizontal. 
Triple  condensing,  high  duty,  horizontal  and  vertical. 

Rotative  or  Crank  and  Fly-Wheel  Type 

Cross   compound   condensing,   high   duty,    horizontal   and 

vertical. 
Double    compound    condensing,    high    duty,     horizontal. 

(Gaskill.) 

Triple  condensing,  high  duty,  horizontal.  (Gaskill.) 
Triple  condensing,  high  duty,  vertical.  (Reynolds.) 
Quadruplex  condensing,  low  duty,  inclined.  (Holly.) 

Beginning  at  the  top  of  the  list,  the  Worthington  type  of 
water  works  pumping  engine  has  been  repeated  to  a  very  much 
greater  extent  than  any  known  form.  In  fact  since  1863,  the 
date  of  its  introduction,  the  duplex  direct  acting  type  has 
been  more  extensively  duplicated  for  water  works  purposes 

166 


f 

VARIOUS  TYPES  AND  CLASSES  167 

than  any  other,  not  even  excepting  the  older  and  original 
direct  acting  type,  the  celebrated  Cornish  engine.  And  since 
the  expiration  of  the  early  Worthington  patents,  the  shops 
of  nearly  all  regular  steam  pump  builders,  wherever  water 
works  machinery  of  moderate  sizes,  say  up  to  5,000,000  gallons 
daily  capacity,  has  been  manufactured,  have  joined  in  swelling 
the  production  of  this  type  of  hydraulic  machinery. 

The  compound  non-rotative,  non-condensing,  horizontal 
machine,  the  first  on  the  list  (see  Fig.  43),  is  likely  the  simplest 
form  in  which  is  it  possible  to  construct  a  pumping  engine  at 
all  acceptable  for  supplying  water  in  a  methodical  manner. 
It  of  course  follows  the  regular  duplex  direct  acting  lines, 
although  the  absence  of  a  condenser  necessitates  even  a  lower 
rate  of  expansion  than  the  rather  low  ratio  of  the  condensing 
machine,  but  it  must  be  remembered  that  the  water  load  is 
added  to  by  the  one  atmosphere  pressure  of  steam  which  must 
be  driven  out  of  the  low  pressure  cylinder  when  no  vacuum  is' 
present  to  help  the  work  along.  There  are  two  high  pres- 
sure cylinders  and  two  low  pressure  cylinders  for  the  steam  end, 
and  generally  one  large  casting  contains  the  two  water  plungers. 
It  has  the  steam  pistons,  pump  plungers,  and  duplex  steam 
valve  gear  constructed  practically  the  same  in  principle  as  in 
the  larger  and  more  refined  classes  of  this  type.  It  is  not  very 
extensively  used  for  water  works  purposes,  upon  the  score  of 
lack  of  steam  economy,  although  the  machine  may  be  bought 
for  comparatively  a  low  price.  However,  in  some  cases,  say 
up  to  1,000,000  gallons  per  day,  where  coal  is  very  cheap  and 
plentiful,  this  class  of  engine  is  occasionally  employed. 

The  second  on  the  list,  the  compound  condensing,  horizontal, 
non-rotative  pumping  engine,  is  fully  described  in  Chapter 
IX  as  the  original  water  works  engine  of  this  type. 

The  third  on  the  list,  the  triple  non-condensing,  horizontal 
machine,  is  practically  the  same  as  the  first  mentioned  at  the 
head  of  the  list,  with  a  third  pair  of  cylinders  added  so  as  to 
use  the  steam  three  times  instead  of  twice.  It  is  not  much 
used  in  water  works  because  the  compound  condensing  does 


PUMPING  ENGINES 

more  with  its  steam  at  almost  the  same  or  perhaps  a  little 
lower  cost  for  plant  including  boilers. 

The  fourth  on  the  list,  the  triple  condensing,  horizontal, 
known  as  the  "low  duty  triple,"  is  the  machine  third  in  the 
list,  with  its  cylinder  proportions  slightly  changed  and  a  con- 
denser added.  This  form  of  the  non-rotative  machine  up  to 
6,000,003  gallons  daily  capacity,  makes  a  very  good  compromise 
between  low  and  high  duty  for  small  and  moderate  sizes  of 
pumping  engines.  Cities  and  towns  pumping  enough  water 
would  be  justified  in  purchasing  a  high  duty  compound  con- 
densing engine,  but  the  economy  of  fuel  is  of  course  just  as 
desirable  in  the  smaller  plants  as  in  the  larger  ones,  and  it  is 
perfectly  plain  that  high  duty  may  be  too  expensive,  for  its 
real  value  must  be  based  upon  the  saving  in  fuel  which  it  can 
effect,  as  balanced  against  the  capital  account  represented  by 
the  interest  on  the  cost  of  the  engine,  and  also  the  cost  of  the 
maintenance  of  the  engine  in  good  order  and  repair.  The 
time  came  when  the  low  duty  compound  condensing  machine 
was  left  too  far  in  the  background  by  the  high  duty  standard 
machine  to  hold  its  place,  and  hence  a  step  forward  within 
the  reach  of  small  and  moderate  buyers  became  necessary. 
The  "low  duty  triple"  meets  the  requirements  in  a  very  satis- 
factory manner. 

The  idea  was  to  produce  a  pumping  engine  so  simple  in 
design  that  its  cost  would  be  comparatively  low,  and  yet  contain 
elements  which,  although  not  by  any  means  ranking  with  the 
cut-off  high  expansion  machines,  nevertheless  would  show  a 
saving  in  coal  that  would  justify  a  slightly  greater  price,  when 
pumping  a  small  quantity  t>f  water,  than  the  low  duty  com- 
pound could  be  bought  for.  It  must  also  equal  the  compound 
practically,  in  low  cost  of  repairs. 

As  already  pointed  out,  this  class  of  the  Worthington  type 
is  a  six  cylinder  machine  at  the  steam  end,  having  the  cylinders 
in  tandem  pairs  with  the  low  pressure  cylinder  at  the  outer  end. 
See  Fig.  44  for  a  general  view  of  the  machine,  and  Fig.  45  for 
a  longitudinal  section  of  the  steam  end.  A  good  deal  of  study 


'So 

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VARIOUS  TYPES  AND  CLASSES  169 

was  given  to  this  engine  with  the  factor  of  accessibility  in  view, 
and  the  successful  arrangement  for  getting  at  the  various  pis- 
tons is  apparent  in  Fig.  45  which  is  a  horizontal  section  through 
the  cylinders.  Each  piston  and  cylinder  may  be  examined 
by  the  removal  only  of  the  respective  cylinder  head.  The 
high  pressure  and  intermediate  pistons  may  be  removed  be- 
.tween  the  high  and  intermediate  cylinders;  while  the  low  pres- 
sure pistons  come  out  at  the  back  end  of  the  machine  in  the 
usual  manner. 

The  steam  valves  are  of  the  Corliss  type  and  located  beneath 
the  cylinders,  thus  giving  a  very  perfect  drainage  and  practi- 
cally preventing  any  moisture  entering  the  cylinders  at  all, 
such  moisture  going  directly  into  the  exhaust  ports  at  once; 
and  it  has  been  demonstrated  in  practice  that  these  engines 
do  not  need  the  usual  drip  valves  on  the  steam  cylinders.  Cut-- 
off valves  are  fitted  to  the  high  pressure  cylinders  only,  and 
the  mechanism  is  arranged  to  cut  off  from  the  half  to  the  three 
quarter  point  in  the  stroke.  The  valve  gear  is  very  simple, 
and  in  principle  like  the  regular  duplex,  modified  of  course  to 
suit  the  Corliss  valve,  and  driving  directly  to  the  valve  arms. 

The  drive  of  the  main  pump  at  each  side  of  the  engine  is 
accomplished  by  attaching  the  plunge  rod  to  a  cross  head  ex- 
tending across  the  framing,  so  as  to  connect  with  the  single  piston 
from  the  high  pressure  and  the  pair  of  rods  from  the  low  pres- 
sure, the  intermediate  piston  being  connected  by  a  single  piston 
rod  back  through  the  head  between  the  intermediate  and  low 
pressure  cylinders,  the  intermediate  piston  driving  directly 
on  to  the  low  pressure  piston  which  in  turn  transmits  the  inter- 
mediate power  to  the  cross  head  by  means  of  the  pair  of  rods 
shown. 

The  efficiency  of  this  class  is  very  satisfactory  in  small  and 
moderate  machines,  say  from  750,000  to  6,000,000  U.  S.  gallons 
per  24  hours,  when  pumping  against  ordinary  water  works 
pressures  of  from  40  to  100  Ibs.  per  square  inch.  The  duty  of 
the  engine  varies  according  to  size  and  other  governing  condi- 
tions, from  70,000,000  to  95,000,000  ft.  lb«>  per  1,000  Ibs.  of 


170  PUMPING  ENGINES 

steam,  some  records  going  as  high  as  80,000,000  ft.  Ibs.  with 
ordinary  steam  just  as  it  comes  from  the  every-day  boiler  plant 
without  allowances  for  entrainment.  An  engine  of  this  type 
and  class  of  2,000,000  U.  S.  gallons  capacity  per  24  hours, 
pumping  against  a  pressure  of  about  80  Ibs.,  has  an  official 
record  on  test  duty  of  82,000,000  ft.  Ibs.  per  100  Ibs.  of  coal 
fired,  without  any  deductions  of  any  kind;  and  its  record  gives 
a  yearly  duty  of  72,000,000  ft.  Ibs.  per  100  Ibs.  of  coal  for  the 
station,  including  banking  and  heating,  although  it  is  very 
difficult  to  see  what  banking  and  heating  have  to  do  with  the 
duty  of  a  pumping  engine. 

The  fifth  on  the  list,  the  compound  condensing  high  duty, 
horizontal  direct  acting  pumping  engine,  is  the  engine  men- 
tioned second  fitted  with  what  is  known  as  a  high  duty  attach- 
ment. A  clear  idea  of  this  engine  is  given  in  Chapter  IX  under 
the  heading  of  the  original  Worthington  pumping  engine. 

The  sixth  on  the  list,  the  triple  condensing,  high  duty  hori- 
zontal and  vertical,  is  a  still  further  development  of  the  non- 
rotative  type  of  pumping  machinery,  and  represents  the  largest 
and  most  economical  pumping  engines  of  this  type.  It  is 
produced  in  capacities  ranging  as  high  as  40,000,000  U.  S. 
gallons  per  24  hours,  and  has  a  record  of  175,000,000  ft.  Ibs. 
of  work  per  1,COO  Ibs.  of  dry  steam. 

The  high  duty  horizontal  triple  condensing,  direct  acting 
or  non-rotative  type  is  shown  in  Fig..  46,  and  the  vertical 
triple  engine  is  illustrated  in  Fig.  47,  the  latter  indicating  a 
class  of  this  type  employed  in  capacities  of  from  20,000,000 
to  40,000,000  U.  S.  gallons  per  24  hours. 

The  seventh  on  the  list  is  the  cross  compound  condensing, 
high  duty  crank  and  fly  wheel  pumping  engine,  which  is  built 
in  both  the  horizontal  and  the  vertical  form.  By  cross  com- 
pound is  meant  that  the  steam  is  transmitted  across  the  engine 
on  its  way  from  the  main  steam  pipes  to  the  condenser,  ex- 
panding and  doing  work  on  its  way.  There  is  a  high  pressure 
steam  cylinder  at  one  side  of  the  machine,  which  takes  its 
supply  of  steam  directly  from  the  boiler  and  exhausts  into  a 


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VARIOUS  TYPES  AND  CLASSES 


171 


172 


PUMPING  ENGINES 


receiver;  and  a  low  pressure  steam  cylinder  at  the  opposite  side 
of  the  machine,  taking  its  steam  from  the  receiver  and  exhaust- 
ing into  the  condenser.  This  type  of  engine  would  be  impos- 
sible for  practicable  operation  in  pumping,  without  the  use  of 


Fig.  47.  —  Worthington  Vertical  High  Duty  Triple. 

the  crank  and  fly  wheel  for  connection  and  regulation;  it  is 
a  very  good  type  of  pumping  engine  where  it  suits  the  condi- 
tions, but  there  are  many  cases  in  water  works  where  the 
unbalanced  operation  of  the  two  sides  of  the  machine  make  it 
undesirable.  Also  where  the  steady  and  full  load  of  reservoir 


OF  THE 
I  IKI  I\/CDCITV 


Y 

VARIOUS  TYPES  AND  CLASSES 


173 


service  or  an  equivalent  load  is  encountered,  the  use  of  the 
cross  compound  engine  does  not  give  the  buyer  that  full  benefit 
of  steam  economy  that  might  be  just  as  well  obtained  by  the 
use  of  a  triple  expansion  machine,  especially  in  cases  of  con- 


Fig.  50.  —  Platt  Iron  Works  Company  Horizontal  Cross  Compound. 

siderable  capacity,  say  from  10,000,000  to  20,000,000  gallons 
and  upward  per  day. 

The  horizontal  cross  compound  pumping  engine  originated 
in  the  attachment  to  a  regular  cross  compound  Corliss  mill 
engine,  of  two  water  pumps,  one  behind  each  steam  cylinder; 
the  plungers  being  driven  by  an  extension  of  the  steam  piston 


174  PUMPING  ENGINES 

rods  through  the  back  steam  cylinder  heads,  and  then  prolong- 
ing these  rods  into  plunger  rods  entering  the  water  cylinders. 
It  is  no  doubt  the  simplest  form  of  the  horizontal  crank  and 
fly  wheel  pumping  engine,  but  on  account  of  very  considerable 
space  required  has  not  been  extensively  used  in  water  works 
plants,  especially  where  new  engines  are  placed  in  old  buildings. 

The  Platt  Iron  Works  Company  of  Dayton,  Ohio,  has  followed 
out  this  idea  in  a  substantial  and  consistent  manner,  and  has 
also  taken  an  important  step  apparently  in  advance  of  most  of 
the  others  so  far  as  concerns  reduction  in  the  cylinder  waste 
room  or  clearance,  by  placing  the  steam  valves  across  the 
cylinder  heads  in  this  type  of  pumping  engine.  The  water 
plungers  are  very  easy  of  access  at  the  free  end  of  the  water 
cylinders;  the  steam  pistons  are  reasonably  accessible  especially 
when  it  is  considered  that  the  modern  steam  piston  requires 
comparatively  little  attention;  and  the  main  pillow  blocks, 
cross  heads,  and  connecting  rods  are  as  easy  to  get  at  as  in  a 
Corliss  mill  engine.  This  company  seems  to  be  making  some 
special  and  apparently  successful  efforts  in  adapting  the  Corliss 
type  of  steam  end  to  various  types  of  pumping  engines,  includ- 
ing direct  acting  or  non-rotative  machinery,  as  may  be  seen  in 
Fig.  56,  which  shows  a  design  of  compound  condensing  engine, 
and  Fig.  57,  which  shows  a  four  cylinder,  cross-triple  engine. 

The  Snow  Steam  Pump  Works  of  Buffalo,  N.  Y.,  reduced 
the  cross  compound  horizontal  pumping  engine  practically  to 
a  regular  although  not  frequently  repeated  type,  by  placing 
the  crank  shaft  between  the  steam  and  water  ends  of  the 
machine,  the  steam  pistons  and  water  plungers  being  rigidly 
connected  together  by  means  of  tie  rods  which  pass  above  and 
below  the  crank  shaft.  The  Allis-Chalmers  Company  of  Mil- 
waukee, Wis.,  also  produce  a  cross-compound  engine  of  this  type, 
and  the  originality  of  design  will  as  a  matter  of  course  be  disputed 
between  these  two  firms.  The  machine  has  a  great  advantage  by 
being  accessible  as  to  pistons  and  plungers,  at  the  outer  ends 
of  the  si  earn  and  water  cylinders,  and  reasonably  so  with  refer- 
ence to  the  main  pillow  blocks  and  connr cting  rods.  There 


Fig.  51.  —  Allis-Chalmers  Vertical  "A"  Frame  Compound. 

"0 


OF  THE 


52. Allis- Chalmers  Vertical  Tower  Frame  Compound  and  Triple. 


VARIOUS   TYPES  AND  CLASSES  175 

have  not  been  very  many  of  these  horizontal  cross  compound 
machines  built,  most  likely  for  the  reason  that  there  are  not  so 
very  many  places  where  they  will  fit  hi  economically,  all  things 
considered.  It  seems  as  though  the  cross  compound  came  too 
late  into  the  field;  the  gap  between  the  low  duty  triple  and  the 
high  duty  triple  is  comparatively  narrow,  and  is  well  taken  care 
of  by  the  regular  and  thoroughly  introduced  types  of  high 
duty  compound  machinery  such  as  the  Worthington  and  the 
Gaskill-Holly  engines. 

Fig.  48,  Fig.  49,  Fig.  50,  Fig.  51,  and  Fig.  52,  show  different 
makes  of  horizontal  cross  compound  pumping  engines,  and  also 
two  different  makes  of  vertical  cross  compound  machines,  all 
designed  and  built  by  leading  engineers  and  manufacturers.  As 
to  economical  results,  there  is  no  reason  in  the  expanding  of 
steam  in  two  cylinders  provided  with  appropriate  cut-off  mech- 
anism, why  this  form  of  machine  within  proper  limits  will  not 
accomplish  as  high  a  record  as  any  other  type,  of  a  similar 
number  of  expansions,  and  similar  circumstances.  In  fact  the 
record  does  show  that  the  results  are  about  the  same  with  com- 
pound machinery  under  equal  ratios  of  expansion  and  mechani- 
cal efficiency,  similar  steam  pressures  and  work  accomplished. 

There  has  been  much  talk  about  high  ratios  of  cylinders  in 
compound  engines,  competing  with  the  triple  engine,  in  steam 
economy;  but  the  secret  of  efficiency  in  high  ratio  compound 
cylinders  is  the  unusually  large  low  pressure  cylinder  incident- 
ally afforded,  and  the  consequent  facility  of  adjustment  of  the 
engine  to  its  load.  But  the  excessive  range  of  temperature 
that  appears  when  too  much  steam  expansion  is  attempted  in 
any  one  cylinder  will  always  prevent  two  cylinders  reaching 
the  economy  of  three  cylinders.  And  aside  from  this,  the  many 
advantages  in  using  three  single  acting  plungers  in  a  pumping 
engine  would  be  enough  to  dispose  of  all  arguments  in  favor 
of  cross  compound  engines,  where  the  cost  and  capacity  are 
favorable  to  the  triple. 

The  eighth  on  the  list,  the  double  compound,  condensing, 
high  duty  horizontal,  crank  and  fly  wheel  pumping  engine,  is 


176  PUMPING  ENGINES 

fully  described  in  Chapter  XI  as  the  Gaskill  engine,  and  enjoys 
the  distinction  of  being  the  first  high  duty  crank-  and  fly- 
wheel pumping  engine,  probably  the  first  high  duty  pumping 
engine  of  any  type,  regularly  built  as  a  standard  or  commercial 
machine. 

The  ninth  on  the  list  has  been  of  limited  use  in  water  works 
plants.  It  is  the  Gaskill  compound  engine  with  an  additional 
pair  of  steam  cylinders,  these  latter  cylinders  forming  the  high 
pressure  cylinders  of  a  six-cylinder  triple  machine  of  the  hori- 
zontal, crank  and  fly-wheel  type.  (See  Fig.  53,  which  gives  a 
very  clear  idea  of  this  machine.)  Its  limited  employment  in 
pumping  stations  is  no  doubt  due  to  the  idea  that  when  the 
step  to  triple  expansion  is  taken,  the  fact  presents  itself  that 
instead  of  stopping  half  way  at  a  compromise  point,  it  is  better 
to  adopt  the  complete  triple  machine,  the  vertical  triple,  three- 
cylinder  engine,  and  thus  simplify  the  machine  and  increase  the 
efficiency  at  the  same  time,  even  though  at  slightly  greater  cost. 

The  tenth  on  the  list  is  the  Reynolds  vertical  triple  expan- 
sion engine,  now  rapidly  taking  the  lead  as  the  ultimate  devel- 
opment of  modern  high  duty  pumping  machinery,  already  hav- 
ing just  about  reached  the  extreme  possibilities  in  expanding 
steam  under  practicable  working  pressures.  This  engine  is 
described  in  Chapter  XII  in  fairly  good  detail. 

The  eleventh  on  the  list,  although  now  obsolete  and  out  of 
the  market,  the  Holly  quadruplex  pumping  engine,  especially 
designed  for  closed  systems  of  pipes,  is  well  worthy  of  mention. 
It  held  an  important  place  in  the  public  water  supply  field 
twenty-five  years  ago,  and  was  well  thought  of  as  a  standard 
machine  in  its  day.  A  description  of  this  type  of  machine  is 
given  in  Chapter  X  as  one  of  the  distinct  types  of  pumping 
engines. 

There  are  in  addition  to  the  foregoing,  several  offshoots  from 
the  Worthington  type  of  high  duty  non-rotative  machinery, 
two  only  of  which  seem  to  be  of  sufficient  prominence  to  call 
for  special  mention — the  d'Auria  and  the  Groshon  engines; 
and  only  one  of  these3  the  d'Auria,  has  been  repeated  sufficiently 


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VARIOUS   TYPES  AND  CLASSES 


177 


to  entitle  it  to  a  place  as  a  regular  pumping  engine  for  public 
water  supply.  Both  of  these  engines  would  come  under  the 
fifth  and  sixth  in  the  list,  that  is,  of  the  non-rotative  type  and 
belonging  to  the  high  duty  compound  and  triple  classes,  as 
they  can  both  be  produced  either  as  compounds  or  triple  expan- 
sion machines,  precisely  upon  the  lines  of  construction  followed 
by  the  Worthington  machinery,  with  differences  in  the  com- 
pensating devices  and  valve  gear. 

The  d'Auria  high  duty  pumping  engine  is  practically  a 
Worthington  machine  fitted  with  a  balancing  or  compensating 
device  of  the  hydraulic  variety,  and  consisting  of  a  liquid  col- 


rr 

J 

, 
y 

^v 

^x 

/ 

x^ 

Fig.  65.  —  Hydraulic  Loop  of  the  d'Auria  Pumping  Engine. 


umn  contained  within  an  inclosed  loop  or  pipe,  connected 
with  a  chamber  which  contains  an  auxiliary  or  compensating 
plunger.  This  plunger  is  attached  to  the  same  rod  that  carries 
the  main  pump  plunger  and  the  steam  pistons  of  the  pumping 
engine.  (See  Fig.  55  for  the  hydraulic  loop,  and  Fig.  54  for  a 
general  view  of  this  class  of  the  non-rotative  type.)  When  the 
engine  is  working,  the  compensator  or  auxiliary  plunger  forces 
the  liquid  in  the  pipe  loop  into  an  alternating  or  pendulum- 
like  motion.  During  the  early  part  of  the  stroke,  before 
the  cut-off,  the  surplus  energy  due  to  the  initial  steam 
is  absorbed  mostly  by  the  hydraulic  column  in  the  loop,  to  be 
given  out  again  during  the  latter  portion  of  the  stroke  when 
the  expanding  steam  has  become  too  weak  to  drive  the  load. 
Of  course  the  object  is,  as  in  the  case  of  the  fly  wheel  of  the 
crank  engine,  or  the  compensating  plungers  of  the  Worthington 


ITS  PUMPING  ENGINES 

engine,  to  equalize  the  inequalities  of  steam  expansion  through- 
out the  strokes  of  the  engine. 

This  class  of  the  non-rotative  type  is  being  built  for  water 
works  pumping  stations  in  sizes  from  1,500,000  to  10,000,000 
U.  S.  gallons  per  24  hours,  and  in  general  design  is  exception- 
ably  good  from  a  mechanical  standpoint.  The  castings  are  of 
unusually  good  design;  and  so  far  as  can  be  seen,  this  engine 
if  properly  placed  upon  a  commercial  basis  and  pushed  with 
the  energy  with  which  some  of  the  others  have  been  handled, 
would  no  doubt  get  its  share  of  business;  for  no  matter  how 
good  the  inventor  or  designer  may  think  his  engine  is,  or  good 
it  really  is,  the  public  practically  knows  nothing  about  it,  and 
it  requires  a  good  deal  of  persistence,  patience  and  hard  work 
to  demonstrate  any  certain  lot  of  facts  in  competition  with 
some  other  facts  opposing. 

The  Groshon  high  duty  non-rotative  pumping  engine  is  a 
pumping  engine  of  the  Worthington  type  fitted  with  Groshon's 
valve  gear  and  compensating  device,  the  valve  gear  being  an 
adaptation  of  the  Corliss  releasing  gear  with  dash  pots;  and  the 
compensating  device  is  a  combination  of  auxiliary  water  cylin- 
ders, levers,  and  connections,  so  arranged  as  to  make  use  of 
the  water  pressure  in  the  main  discharging  pipe,  to  equalize 
the  inequalities  of  the  steam  expansion.  The  machine  seems 
to  be  practicable,  but  very  few  have  been  built  and  put  into 
service ;  although,  as  in  the  case  of  the  d' Auria  engine,  commer- 
cial energy  properly  and  liberally  applied  would  no  doubt  result 
in  the  use  of  this  engine  to  a  corresponding  extent.  Fig.  58 
shows  a  general  view  of  the  Groshon  pumping  engine  above  the 
floor  line,  and  Fig.  59  shows  a  side  elevation  exhibiting  the 
working  parts  of  the  valve  gear  and  compensating  device. 

Aside  from  the  regular  types  and  classes  of  pumping  engines 
for  water  works  which  have  gradually  taken  their  places  from 
time  to  time,  there  have  been  quite  a  number  of  attempts  at 
special  designs  which  have  been  seldom  or  never  repeated; 
and  such  engines  have  no  doubt  been  fondly  looked  upon  by 
their  designers  at  the  time  of  production,  as  the  perfection  of 


I 

w 

9 
•a 

J 


s 

I 


VARIOUS  TYPES  AND  CLASSES  179 

accomplishment,  to  be  copied  and  repeated  by  engineers  for  all 
time  to  come.  Of  course  all  new  machines  which  represent 
radical  departures  from  well-trodden  paths  are  of  special 
design,  and  the  attempts  to  make  them  successful  and  admir- 
able are  extremely  earnest  and  sincere.  But  it  has  been 
observed  that  the  most  valuable  and  enduring  advances  have 
been  made  along  the  lines  of  evolution  more  or  less  slowly;  the 
few  brilliant  and  marked  examples  now  and  then  taking  their 
places  as  a  sort  of  punctuation  in  the  general  progress. 

And  so  it  may  be  noted  that  during  the  years  of  develop- 
ment of  what  may  be  called  commercial  pumping  machinery, 
although  it  was  not  considered  as  such  in  the  early  days,  for 
water  works,  from  1885  to  1892  occasional  designs  of  a  special 
nature  with  the  aim  of  much  better  steam  economy  mostly 
in  view  came  out  from  time  to  time ;  and  no  doubt  these  special 
engines  spurred  the  makers  of  the  regular  products  to  greater 
efforts.  Long  and  heated  arguments  were  indulged  in  by 
the  different  advocates  of  various  ideas,  all  tending  to  fix  the 
lines  of  average,  where  capital  and  coal  accounts  could  meet 
upon  (fommon  ground,  and  where  the  buyer  could  make  the 
best  investment  all  things  considered. 

The  more  notable  special  pumping  engines  giving  duties 
above  100,000,000  ft.  Ibs.  per  1,000  Ibs.  of  steam,  were  the 
Corliss  Paw  tucket  cross  compound,  horizontal  engine  of  1878; 
the  Leavitt  Lawrence  compound  beam  engine  of  1879;  the 
Reynolds  Milwaukee  compound  beam  engine  of  1881.  These 
engines,  however,  although  clearly  demonstrating  the  possibil- 
ities of  refinement  along  the  old  lines  of  steam  jacketing, 
high  steam  pressures,  steam  expansion,  condensers,  and  air 
pumps,  were  too  costly  to  justify  their  general  adoption  in 
water  works  service,  even  though  they  did  show  their  ability 
in  the  line  of  much  greater  steam  economy. 

The  Corliss  Pawtucket  engine  is  shown  in  Fig.  60,  the  Lea- 
vitt Lawrence  engine  in  Fig.  61,  and  the  Reynolds  Milwaukee 
engine  in  Fig.  62. 

Among  the   older   and  interesting  pumping  engines  which 


180 


PUMPING  ENGINES 


VARIOUS   TYPES  AND  CLASSES 


182 


PUMPING    ENGINES 


have  never  been  repeated  on  account  of  cost  and  other  objec- 
tions, but  in  which  it  was  sought  to  excel  the  performance  of 
the  Cornish  engine  of  70  years  ago,  and  previous  to  the  advent 
of  the  so-called  "high  duty"  engines  already  referred  to, 
there  might  be  mentioned  the  Shields  engine,  a  Bull  Cornish 


Fig.  60.  —  Corliss  Pawtucket  Pumping  Engine,  by  George  H.  Corliss. 

as  nearly  as  it  resembled  anything,  at  Cincinnati,  Ohio;  the 
full  Cornish  engine  of  Shedd  at  Providence,  R.  I.;  the  Lowry 
engine  at  Pittsburg,  Pa.  And  there  were  a  few  others  hardly 
of  enough  importance  to  mention  here  and  which  perhaps  it 
will  be  better  to  permit  to  sleep  on  in  unknown  resting  places, 
although  they  no  doubt  pointed  a  useful  even  if  painful  lesson 
at  the  time  of  their  design  and  production. 


ERASMUS    D,   LEAVITT, 


VARIOUS  TYPES  AND  CLASSES 


183 


Fig.  61, — Leavitt  Lawrence  Pumping  Engine,  by  E.  D.  Leavitt. 


184 


PUMPING  ENGINES 


Fig.  62. —Reynolds  Milwaukee  Pumping  Engine,  by  Edwin  Reynolds. 


CHAPTER   XIV 

PUMPING  ENGINES  ADAPTED  TO  CONDITIONS 

THE  proper  adaptation  of  a  pumping  engine  to  the  condi- 
tions to  be  met  in  service,  is  the  key  to  the  highest  practical 
efficiency.  Reservoir  work,  or  the  work  of  pumping  only  into  a 
storage  or  distributing  reservoir,  and  with  the  force  main  having 
no  connection  whatever  with  any  of  the  distributing  systems, 
is  no  doubt  the  easiest  and  most  economical  task  that  pumping 
machinery  is  called  upon  to  perform.  But  even  at  that,  there 
are  as  simple  as  the  proposition  seems  at  first  sight,  some 
important  items  to  be  carefully  looked  out  for.  In  the  matter 
of  steam  economy  alone,  there  are  needs  of  reasonable  consider- 
ations in  connection  with  other  details.  There  are  advocates 
of  high  piston  speed,  of  high  steam  pressure,  of  high  rate  of 
revolution,  and  other  singled  out  and  isolated  factors.  But 
the  general  combination  wherein  the  machine  best  meets  the 
conditions  is  what  will  yield  the  best  results,  and  not  the 
exploiting  of  any  particular  seemingly  important  factor  by 
itself.  And  as  an  example  of  this  it  may  be  noted  that  the 
pumping  engine  in  this  country,  if  not  in  the  world,  which  a 
year  ago,  April,  1906,  held  the  high  duty  record  per  1,000  of 
steam,  has  the  following  set  of  conditions  to  work  under: 

Capacity  per  24  hours,  15,000,000  U.  S.  gallons. 

Piston  speed,  197  feet  per  minute. 

Rotative  speed,  19.7  revolutions  per  minute. 

Water  load  against  pumps,  126  Ibs.  pressure,  290  ft.  head. 

Steam  pressure  per  gauge,  126  Ibs. 

Indicated  power,  802  horse  power. 

Mechanical  efficiency,  96  per  cent. 

Steam  per  hour  per  indicated  horse  power,  10.68  Ibs. 

Duty  per  1,000  Ibs.  of  steam,  179,450,250  ft.  Ibs. 

185 


186 


PUMPING  ENGINES 


With  reference  to  high  piston  speed,  the  best  record  known 
to  the  writer  as  to  pumping  engines  is  607  feet  per  minute, 
where  the  duty  per  1,000  Ibs.  of  steam  was  157,843,000  ft.  Ibs., 
showing  that  high  piston  speed  alone  will  not  answer. 

With  reference  to  high  steam  pressure,  the  record  seems  to 
be  200  Ibs.  per  gauge  and  a  duty  of  149,500,000  ft.  Ibs.,  show- 
ing that  high  steam  pressure  in  the  absence  of  other  ruling 
conditions  or  proper  fitness,  falls  short  of  the  best  perform- 
ance. 

Regarding  thermal  efficiency,  or  the  actual  economy  of  heat 
employed  with  reference  to  absolute  temperatures,  even  the 
greatest  thermal  efficiency  does  not  in  the  presence  of  adverse 
conditions  in  some  other  directions,  enable  the  engine  with 
a  very  high  thermal  efficiency  to  equal  the  engine  working 
under  a  better  general  fitness  of  things,  as  will  be  seen  by  the 
following : 


THERMAL  EFFICIENCY. 

DUTY  PER 
1,000  LBS.  OF  STEAM. 
Foot  Pounds. 

22.80 
21.63 
21.00 
20.85 

20.78 

149,500,000 
178,497,000 
179,454,250 
173,620,000 
176,419,600 

What  has  been  considered  for  some  time  the  world's  record 
for  general  all  around  efficiency  for  a  pumping  engine  is  as 
follows : 

Capacity  per  24  hours,  30,000,000  U.  S.  gallons. 

Steam  pressure  per  gauge.  185  Ibs. 

Piston  speed,  195  feet  per  minute. 

Duty  per  1,000  Ibs.  of  steam,  178,497,000  ft.  Ibs. 

Duty  per  million  b  eats  units,  163,925,300  ft.  Ibs. 

Steam  per  indicated  horse  power  per  hour,  10.335  Ibs. 

Thermal  efficiency,  21.63  per  cent. 

Mechanical  efficiency,  96  per  cent. 

Rotative  speed,  17.73  revolutions  per  minute. 


.  ,  MPING  ENGINES  ADAPTED   TO  CONDITIONS      187 

The  complaint  has  often  been  made  that  pumping  engines 
do  not  give  so  high  a  duty  in  regular  service  as  during  the 
official  test  with  experts.  In  general  terms  this  might  be 
admitted  and  because  the  experts  know  how  to  adjust  the  engine 
better  and  how  to  operate  it  more  closely  to  conditions  found 
to  exist  than  the  running  engineer  usually  found  in  pumping 
stations;  and  this  difference  in  operation  in  favor  of  the  expert 
is  because  the  expert,  by  his  more  extensive  knowledge  of  the 
subject,  is  a  more  valuable  and  a  higher  paid  man  than  the 
regular 'attendant.  But  it  would  not  pay  for  all  the  actual  and 
practical  difference  in  economy,  to  employ  a  scientific  and 
professional  expert  to  operate  a  pumping  station,  although 
for  purposes  of  contract  comparisons  the  very  best  work  of 
the  engineer  is  sought  to  be  brought  out  by  the  contractor, 
and  this  is  just  what  the  expert  does,  leaving  it  to  the  regular 
running  engineers  to  approximate  as  nearly  as  they  can  under 
every-day  conditions  and  the  many  cares  of  the  situation, 
the  pace  ?et  at  the  official  test.  But  aside  from  the  fine  ad^ 
justments  which  the  expert  is  able  to  make  in  the  engine  so  as 
to  completely  adapt  the  machine  to  its  work  at  the  time  of  the 
test,  while  the  engine  cannot  be  expected  to  keep  up  to  the 
fine  adjustment  in  the  hands  of  its  regular  attendants,  any 
material  falling  off  in  duty  can  be  traced  to  changed  conditions. 

For  reservoir  work  exclusively,  consisting  of  pumping  to  a 
reservoir  through  an  independent  main,  and  in  the  absence 
of  service  pipes  for  supplying  consumers,  the  fullest  liberty 
can  be  allowed  in  selecting  the  type  of  pumping  engine  to  be 
used;  and  any  reasonable  type  or  class  in  the  use  of  which 
the  economy  of  steam  and  coal  would  be  satisfactory  might 
be  installed.  But  when  the  service  of  supplying  consumers 
comes  into  the  question,  and  where  the  water  from  the  pump- 
ing station  is  sent  through  street  distribution  pipes,  the  types 
of  machinery  must  be  restricted  to  those  which  will  give  rea- 
sonable smoothness  in  operation  and  a  great  deal  of  freedom 
from  pulsation.  The  system  not  infrequently  met  with  of 
having  the  distributing  mains  supplying  the  consumers  situated 


188  PUMPING  ENGINES 

between  the  pumping  station  and  the  reservoir,  the  gen- 
eral consumption  satisfying  its  demands  and  the  surplus  going 
on  into  the  reservoir  located  somewhere  beyond  the  main  dis- 
tribution, furnishes  a  case  in  point :  and  a  two  plunger  pumping 
engine  with  180  degree  crank  pins  will  require  excessive  air 
chambers  to  enable  it  to  give  any  decent  approach  to  satis- 
factory service;  in  fact  any  type  or  class  of  rough  working 
engine  will  under  such  conditions  cause  a  great  deal  of  trouble 
and  complaint.  Going  a  step  further,  we  have  the  closed 
system,  often  known  in  some  parts  of  the  country  as  the  "  Holly 
System, "  where  a  closed  circuit  of  pipes  is  used  without  stor- 
age or  free  delivery,  and  in  fact  without  any  delivery  aside 
from  the  consumers'  supply  pipes  and  the  inevitable  leakages; 
in  such  a  system  of  course  the  pumping  machinery  should  have 
the  smoothest  possible  delivery,  and  be  capable  of  the  closest 
practical  automatic  regulation.  Steam  economy  takes  a  third 
or  fourth  position  under  the  closed  circuit,  and  certainty  of 
pumpage  supply,  steadiness  of  pressure,  and  promptness  in 
responding  to  fire  alarms  are  the  most  important  factors  in 
the  system.  Such  systems  are  mostly  used  in  the  smaller 
cities  found  in  the  flat  regions  of  the  middle  west;  those  of 
fairly  good  size,  say  from  25,000  to  100,000  population  usually 
have  stand  pipes  in  connection  \vith  what  would  otherwise 
come  under  the  head  of  closed  systems.  Where  the  closed 
system  of  pipes  becomes  of  considerable  extent  and  especially 
where  stand  pipes  are  attached  to  such  systems,  the  pumping 
engines  can  be  proportioned  so  that  they  will  divide  the  work 
up  into  units  of  quantity,  and  then  one  or  two  engines  might 
be  operated  practically  under  reservoir  conditions  so  far  as 
pumping  nearly  or  quite  up  to  capacity  is  concerned;  but  the 
ever  present  liability  of'fire,  which  will  call  for  an  immediate 
and  great  increase  in  the  pumpage,  it  being  remembered  that 
there  is  absolutely  no  storage  aside  from  what  is  in  the  source  of 
supply  and  the  pump  wells,  requires  that  the  running  engines 
must  be  kept  well  within  their  capacity  so  as  to  be  available 
for  quick  increase  in  their  delivery ;  reserves  being  kept  in  cons- 


PUMPING  ENGINES  ADAPTED  TO  CONDITIONS       189 

slant  readiness  to  supplement  the  machinery  working  on  the 
domestic  supply  if  the  demands  for  fire  service  become  urgent. 

It  i night  be  appropriate  to  this  branch  of  the  subject  to 
mention  types  and  classes  of  pumping  engines  best  adapted 
to  the  various  conditions  of  service;  they  would  be  as  follows: 

Pumping  Engines  for  Reservoir  Service  Only. 

Horizontal  engines  with  two  double  acting  plungers. 
Vertical  engines  with  two  single  acting  plungers. 
Vertical  engines  with  two  differential  plungers. 
Vertical  engines  with  one  bucket  and  plunger. 
Vertical  engines  with  four  single  acting  plungers. 
Vertical  engines  with  three  single  acting  plungers. 
Direct    acting   vertical    engines    with    two    double    acting 
plungers. 

Pumping  Engines  for  Reservoir  and  Distributing  Service. 

Horizontal  engines  with  two  double  acting  plungers. 
Direct   acting   vertical    engines   with    two    double   acting 

plungers. 

Vertical  engines  with  three  single  acting  plungers. 
Vertical  engines  with  four  single  acting  plungers. 

Pumping  Engines  for  o,  Closed  System  of  Distributing  Pipes. 

Horizontal  engines  with  two  double  acting  plungers. 
Vertical  engines  with  four  single  acting  plungers. 
Vertical  engines  with  three  single  acting  plungers. 
Direct    acting   vertical    engines    with    two    double    acting 
plungers. 

In  buying  and  installing  a  pumping  engine,  there  seems  to 
be  a  certain  procedure  which  has  come  to  be  adopted  during 
the  gradual  development  of  the  business,  and  although  shorter 
and  bolder  courses  may  at  times  be  followed,  upon  the  whole 
it  will  no  doubt  be  found  that  the  natural  evolution  in  the 


190  PUMPING  ENGINES 

matter  is  a  pretty  safe  guide  to  follow.  It  has  seemed  to  some 
at  times  as  though  the  mere  statement  of  the  requirements 
to  be  met  was  all  sufficient  for  the  attraction  of  competition, 
and  that  the  would-be  buyer  could  be  furnished  with  all  the 
necessary  information  and  details  relating  to  what  he  was  to 
get  for  his  money,  by  the  competitors  themselves.  This  seems 
beautifully  simple,  but  there  are  certain  attributes  in  human 
nature  which  completely  defeat  most  of  such  efforts.  Each 
bidder  wants  the  work;  and  as  the  object  and  aim  of  compe- 
tition is  to  get  the  most  and  best  for  the  money,  the  result  is 
that  the  party  with  the  lowest  bid  tries  to  convince  the  buyer 
that  his  machine  is  upon  equal  terms  with  the  others,  and  he 
has  the  lowest  figures;  while  a  higher  or  even  the  highest 
bidder  tries  to  convince  the  buyer  that  he  has  very  much  the 
best  proposition,  although  at  a  higher  figure  or  the  highest 
figure.  The  buyer's  best  course  may  be  upon  a  middle  ground 
somewhere  between  the  highest  and  lowest;  but  he  does  not 
know  if  unfamiliar  with  the  minutiae  of  the  subject;  and  when 
he  sees  the  figures  varying  100  per  cent  from  the  lowest  to  the 
highest  for  what  he  supposes  ought  to  mean  the  same  thing, 
he  is  entirely  at  sea,  and  begins  looking  about  him  for  some 
sort  of  help  out  of  his  dilemma. 

The  wide  open  call  for  proposals  for  a  pumping  engine  will 
result  in  this  state  of  affairs  sometimes,  because  certain  vital 
details  are  not  specified  in  the  call  for  bids,  and  different  bid- 
ders will  offer  machinery  to  be  run  at  all  sorts  of  speeds,  the 
main  object  seeming  to  be  to  make  the  lowest  price;  and, 
although  the  lowest  price  accompanied  by  proper  conditions,  ade- 
quate dimensions,  etc.,  ought  to  be  the  one  chosen,  it  behooves 
the  buyer  to  be  certain  that  he  is  safe  in  his  selection.  Of 
course  this  brings  up  the  question  of  professional  or  expert 
advice  in  making  a  proper  selection,  and  the  logic  of  this  is 
that  it  will  be  better  to  have  competent  specifications  prepared 
in  advance,  than  to  endeavor  to  select  a  proper  proposal  from 
the  "grab  bag"  collection  liable  to  develop  from  the  open  call. 

The  matter  of  specifications  would  seem  at  first  glance  to  be 


I 
PUMPING  ENGINES  ADAPTED   TO  CONDITIONS      191 

very  simple,  and  perhaps  it  is,  to  those  builders  who  under- 
stand, and  have  the  courage  to  offer  what  they  really  know 
ought  to  be  furnished;  but  the  ever  present  grind  known  by  the 
name  of  competition,  coupled  with  the  strongly  grounded  idea 
that  a  contract  should  go  to  the  lowest  bidder,  will  assert  itself 
and  interfere  with  the  fairly  rational  treatment  of  the  subject. 
Aside  from  this  there  is  a  tendency  amounting  to  a  determina- 
tion at  times,  to  stipulate  that  the  builder  of  pumping  engines 
must  provide  all  subfoundations,  foundations  proper,  do  ex- 
cavating, cut  into  and  replace  masonry,  floors,  walls,  and  what- 
ever may  be  changed  in  the  course  of  the  installation  of  the 
machinery;  thereby  inflicting  upon  the  maker  of  machinery  a 
lot  of  work  entirely  and  completely  outside  of  his  legitimate 
business  and  occupation.  The  writer  holds,  and  is  encouraged 
by  experience  in  the  belief,  that  the  best  course  for  a  buyer 
to  pursue  with  reference  to  his  own  interest  is  to  exempt  the 
engine  builder  from  all  work  and  responsibility  outside  of  the 
machinery  itself,  even  to  the  painting  of  it,  leaving  him  only 
that  which  he  is  prepared  to  handle,  and  so  leave  his  mind  free 
from  the  haunting  shadows  of  matters  foreign  to  his  busi- 
ness and  which  he  cannot  meet  without  a  certain  element  of 
uncertainty  as  to  cost,  and  the  reflection  of  which  most  surely 
comes  back  to  the  buyer  in  the  shape  of  increased  price  by  rea- 
son of  percentages  added  by  the  machinery  maker  to  cover 
possible  contingencies  of  which  he  cannot  accurately  inform 
himself  beforehand. 

Let  us  map  out  a  course  which  would  be  followed,  indeed 
has  been  followed,  with  very  satisfactory  results,  whether  the 
purchaser  be  a  private  corporation  or  individual,  or  a  city 
hedged  about  by  legal  requirements  in  the  making  of  a  con- 
tract. First  it  should  be  stated  in  some  sort  of  an  announce- 
ment that  the  proposals  will  be  received  at  a  certain  hour, 
date,  and  place;  and  putting  all  upon  an  equitable  footing 
with  sealed  proposals.  General  data  should  be  stated  for 
the  information  of  the  intending  bidders,  arranged  in  a  con- 
venient form  so  that  those  at  a  distance  need  not  go  amiss  in 


192  PUMPING  ENGINES 

preparing  a  proposal,  or  put  under  the  actual  necessity  of  send- 
ing some  one  to  investigate.  Cases  of  course  differ;  sometimes 
the  new  machinery  is  to  go  into  an  old  building,  and  some- 
times a  new  building  is  to  be  provided  for  its  accommodation, 
so  it  may  not  be  practicable  to  lay  down  a  hard  and  fast  rule; 
but  the  general  data  from  an  actual  case  may  give  some  idea 
of  the  requirements: 

Static  water  pressure  at  the  level  of  engine  room  floor. 

Static  water  pressure  from  floor  to  level  of  water  in  well. 

Allowance  added  for  friction  in  force  main. 

Allowance  added  for  friction  in  suction  main. 

Total  working  load  on  the  plungers. 

Steam  pressure  at  the  engine  throttle. 

Available  clear  height  above  the  engine  room  floor. 

Engine  room  floor  to  basement  floor,  vertically. 

Available  distance  across  engine  room. 

Wall  to  wall  of  engine  room,  inside  across. 

Available  on  floor  lengthwise  of  engine  room. 

Available  in  basement  lengthwise  of  engine  room. 

Distance  from  building  wall  to  pump  well. 

Air  chamber  required  at  inboard  end  of  suction  pipe. 

Air  compressor  required  for  force  main  air  chamber. 

It  also  seems  to  be  desirable  to  state  at  least  closely  approxi- 
mate, the  required  length,  or  the  stopping  place  on  the  con- 
tractor's part,  of  the  suction,  delivery,  and  steampipes,  and 
in  these  and  other  items  remove  to  the  utmost  extent  any  and 
all  uncertainties,  so  that  the  builder  of  pumping  engines  may 
be  able  to  figure  upon  some  exact  basis.  In  fact,  a  clear  and 
comprehensive  statement  of  the  work  which  the  buyer  wants 
done  will  help  greatly  in  the  matter,  and  save  a  great  deal 
more  money  than  it  will  cost  to  make  such  a  statement.  A 
general  outline  of  the  work  to  be  done,  modified  of  course  by 
conditions  in  different  cases,  would  call  for  the  making  of  the 
design;  furnishing  general  and  detailed  drawings  or  blueprints; 
and  erecting  in  the  pumping  station  upon  foundations  to  be 


PUMPING  ENGINES  ADAPTED   TO  CONDITIONS     193 

furnished  and  built  by  the  buyer,  in  accordance  with  the  de- 
tailed blueprints,  templates  and  anchor  bolts,  furnished  by 
the  engine  builder;  a  pumping  engine  of  the  desired  type  and 
class,  together  with  appurtenances,  connections,  piping  and 
fixtures  within  the  engine  room,  complete  and  ready  for  con- 
tinuous service. 

A  call  for  detail  drawings  or  working  plans  of  a  pumping 
engine  by  a  buyer  is  not  looked  upon  favorably  by  some 
bidders,  as  it  is  considered  to  be  rather  an  exposure  of  trade 
secrets ;  but  in  some  cases  of  public  work  there  is  a  legal  require- 
ment to  the  effect  that  all  details  of  a  contract  must  be  made 
public  and  submitted,  at  least  so  far  as  the  Board  or  other 
public  body  officially  making  the  purchase  is  concerned.  At 
any  rate,  even  if  the  detail  drawings  should  be  suppressed, 
a  clever  draughtsman  could  produce  upon  paper  a  very  close 
imitation  of  any  machine  in  operation,  which  might  be  open 
to  public  observation,  and  which  as  a  rule  water  works  engines 
are.  And  in  addition  to  this  opportunity  for  copying,  the 
technical  journals  publish,  from  time  to  time,  notable  speci- 
mens of  all  kinds  of  engines  and  machinery  nearly  enough  in 
detail  to  afford  a  pretty  good  guide  as  to  capacity,  strength, 
and  detail  of  construction. 

Some  of  the  first  things  needed  to  be  known  by  the  builders 
are  the  conditions  of  service  under  which  the  engine  is  to  oper- 
ate. This  can  be  conveniently  made  known  by  stating  the 
number  of  gallons  required  to  be  pumped  in  twTenty-four  hours, 
giving  the  total  water  load  upon  plungers,  including  friction 
of  suction  and  delivery  mains,  static  head,  point  and  manner 
of  the  delivery  of  the  water,  and  making  this  statement  in  a 
positive  manner,  thus  releasing  the  engine  builder  completely 
from  all  responsibility  for  the  details  making  up  the  total  load, 
but  requiring  of  him  an  engine  capable  of  delivering  the  given 
quantity  of  water  against  the  aggregate  working  pressure 
under  the  stated  conditions. 

In  the  matter  of  design  of  a  pumping  engine,  under  speci- 
fications drawn  closely  enough  to  indicate  the  type  desired 


194  PUMPING    ENGINES 

clearly  and  unmistakably,  the  actual  design  may  be  well  left 
to  the  builder,  the  stipulation  being  made  that  the  engine 
if  to  go  into  a  building  already  in  existence,  must  conform 
reasonably  to  its  proposed  surroundings,  so  that  proper  and 
convenient  space  about  its  various  parts  may  be  assured.  In 
the  matter  of  adapting  this  or  that  general  type  of  machinery 
to  any  particular  work  or  service,  perhaps  the  buyer  might 
profit  by  independent  expert  advice,  so  as  to  guard  against 
the  well  meaning  but  misguided  zeal  of  makers  possessed  with 
strong  desires  of  selling  machinery  which  might  not  possibly 
represent  the  very  best  investment  for  the  buyer,  but  which 
might  incidentally  give  its  maker  and  advocate  some  trifling 
advantages  over  competitors  in  making  a  contract. 

The  length  of  stroke  is  a  very  important  governing  detail 
in  fixing  the  cost  of  a  pumping  engine,  as  so  many  other  details 
hinge  upon  this  one ;  and  there  is  no  good  reason  for  not  stating 
the  stroke  of  the  pistons  and  plungers,  and  their  speed  as  well 
either  or  both  in  feet  of  travel  and  revolutions  per  minute 
giving  the  allowance  of  excess  desired  in  the  plunger  capacity. 
The  buyer  might  just  as  well  place  all  competitors  upon  an 
equal  footing  at  once,  leaving  very  little  to  argument  or  un- 
certainty, and  he  will  find  that  much  the  easiest  and  more 
economical  way  of  dealing  with  the  matter.  Subterfuges 
relating  to  percentages  of  plunger  diameter  to  length  of  stroke 
are  sometimes  indulged  in  for  the  purpose  of  stipulating 
dimensions,  but  by  far  the  better  way  is  to  come  right  out  with 
the  desired  proportions  of  the  water  end  of  the  machine/  con- 
forming of  course  to  good  practice,  but  leaving  the  steam  fac- 
tor largely  to  the  builder  on  account  of  the  duty  guarantee 
generally  required.  The  writer  has  observed  cases  wherein  it 
would  have  been  much  better  to  appoint  the  experts  before 
buying  the  machine  than  to  wait  until  after  completion  for 
the  regulation  test  of  the  machinery;  and  for  the  reason  that 
even  where  the  designing  is  left  to  the  builder,  certain  stipula- 
tions covering  principles  of  construction  and  proportion  if 
properly  carried  out  will  insure  the  results  asked  for  by  the 


PUMPING  ENGINES  ADAPTED  TO  CONDITIONS     195 

buyer,  and  all  the  experts  would  need  to  decide  would  be 
whether  or  not  these  stipulations  had  actually  been  met;  a 
test  much  more  readily  and  decisively  accomplished  than  some 
of  the  ends  aimed  at  during  the  test  after  construction. 

For  example,  we  know  that  a  pumping  engine  at  a  given 
speed  with  certain  diameter  of  plungers  and  length  of  stroke, 
wrill,  when  properly  made,  displace  just  so  much  water,  the 
construction  and  workmanship  being  the  guide  as  to  capa- 
bility. We  also  know  from  records  and  experience  that  cer- 
tain proportions  in  the  construction  of  steam  cylinders  and 
appurtenances  will  perform  safely  certain  economical  efficien- 
cies; the  entrainment  of  water  in  the  steam,  or  the  leakage 
of  a  force  main  between  the  engines  and  the  reservoir,  will  not 
have  any  bearing  upon  these  facts  as  points  of  design  and 
construction  in  the  engine.  If  the  buyer  is  suffering  from 
bad  boilers  and  force  mains,  the  engine  builder  cannot  help 
him  out  by  modifying  the  machinery.  Give  the  engine  builder 
dry  saturated  or  superheated  steam  for  his  engine  or  the 
equivalent  allowances  therefor,  and  then  take  the  water  away 
from  his  pump  under  the  stipulated  load,  and  that  is  as  far  as 
he  can  fairly  be  held  responsible  for  results. 

The  various  parts  of  the  machinery  should  be  of  plain  and 
substantial  desig-i  writh  appropriate  shapes  and  forms  adapted 
to  the  special  purpose;  the  principal  aims  being  for  ample 
strength,  great  reliability,  good  mechanical  effects,  etc.  Where 
the  design  is  made  by  the  builder,  and  the  work  is  in  competent 
hands,  there  is  not  very  much  to  say,  but  there  is  no  harm 
for  the  buyer  or  his  representative  to  know  that  the  bedplates 
and  framing  will  be  designed  so  as  to  prevent  loss  of  alignment, 
or  undue  strains,  or  changes  of  load  distribution,  from  changes 
of  temperature  or  other  causes;  castings  so  designed  as  to 
avoid  objectionable  changes  of  section  with  reference  particu- 
larly to  shrinkage  strains;  reinforcement  of  the  body  of  the 
casting  next  to  the  flanges,  proper  fillets,  rounded  corners, 
reentering  angles,  and  all  such  details  which  may  just  as  well 
be  had  at  the  same  price  as  something  less  desirable;  the  de- 


196  PUMPING   ENGINES 

sirable  machinery  coming  as  much  or  more  from  a  thorough 
knowledge  of  design  and  construction,  than  from  an  advance 
in  price  asked  by  the  builder. 

The  general  construction  and  arrangement  of  the  pump- 
ing engine  will  of  course  depend  upon  whether  it  is  horizontal 
or  vertical,  as  either  one  of  these  distinctive  types  will  follow 
lines  peculiar  to  itself;  also  depending  upon  whether  the  type 
will  be  of  the  crank  and  fly  wheel  or  the  direct  acting  vari- 
ety, that  is  to  say,  rotative  or  non-rotative.  In  drawing  up 
specifications  for  pumping  engines  upon  the  part  of  the  buyer, 
it  is  not  good  policy  to  go  too  far  in  the  direction  of  actual 
design  or  even  dimensions;  but  rather  to  set  forth  the  con- 
ditions and  requirements  to  a  pretty  exact  degree,  and  by 
so  doing  the  competition  will  be  kept  within  certain  restric- 
tions, a  good  close  and  real  competition  on  figures  will  be  ob- 
tained, and  a  great  variety  of  bids  on  machines  most  of  which 
would  not  be  wanted,  kept  from  complicating  the  efforts  to 
secure  the  type  or  class  of  machine  really  wanted  and  best 
adapted  to  the  work  to  be  done  in  the  current  service  of  the 
water  works  plant.  The  writer  can  recall  a  recent  case,  where 
in  ten  or  twelve  bids  from  different  concerns  representing  the 
best  manufacturers  of  pumping  machinery  in  the  country, 
with  business  headquarters  situated  hundreds  of  miles  apart, 
the  dimensions  given  by  the  bidders  for  the  machinery  pro- 
posed to  be  furnished  were  alike  in  a  large  majority  of  the 
offers,  and  the  few  which  differed  from  the  majority  differed 
but  slightly.  The  bids  reduced  to  equal  terms  did  not  vary 
more  than  five  per  cent.  In  the  specifications  under  which  all 
of  the  proposals  were  made,  not  a  dimension  excepting  the 
length  of  stroke  of  the  engine  was  mentioned,  but  the  condi- 
tions of  service  were  pinned  down  so  closely  that  practically 
all  of  the  bidders  arrived  at  the  same  conclusion  regarding  the 
machines.  A  case  of  the  opposite  character  is  also  recalled, 
where  the  writer  was  called  in  to  untangle  a  snarl  of  bids;  the 
highest  being  more  than  100  per  cent  above  the  lowest.  This 
condition  was  the  result  of  a  wide  open  specification  of  very 


PUMPING  ENGINES  ADAPTED  TO  CONDITIONS        197 

indefinite  meaning,  and  wherein  very  few  particulars  were 
given.  The  bids  were  all  rejected,  and  a  new  specification 
resulted  in  a  good,  clean  competition  with  the  figures  about 
two  thirds  of  the  highest  bids  received  under  the  first  call, 
and  with  the  different  bids  pretty  close  together. 

The  question  as  to  what  type  of  pumping  engine  is  required 
needs  careful  consideration;  whether  horizontal,  vertical,  triple 
expansion,  compound  or  double  expansion,  fly-wheel,  direct 
acting,  and  all  other  matters  and  facts  likely  to  have  an  impor- 
tant bearing  upon  the  subject,  should  be  taken  into  account  in 
making  a  selection.  In  fact,  the  type  or  class  of  engine  can  be 
pretty  thoroughly  sifted  down,  and  then  the  competition 
called  for  upon  lines  suited  to  the  particular  case  in  hand,  and 
so  avoid  the  complications  and  uncertainties  resulting  usually 
from  the  wide  open  specification.  It  is  best  to  set  forth  very 
plainly  the  requirements  to  be  met,  the  guarantees  expected, 
and  the  terms  of  payment  proposed;  stating  the  various  con- 
ditions under  which  the  water  is  to  be  pumped,  the  duty  ob- 
tained, water  pressure,  steam  pressure,  piston  speed,  length  of 
duty,  test,  etc.,  etc.  Also  stating  penalty,  bonus,  or  damages, 
and  the  ultimate  action  of  the  buyer  to  be  expected  in  case 
the  engine  fails  to  meet  the  contract,  or  falls  short  a  certain 
amount  of  the  contract  requirements. 


CHAPTER  XV 
INSTALLATION  OF  PUMPING  ENGINES 

THE  type  and  class  of  the  pumping  engine  having  been  decided 
upon  as  the  best  for  the  service  under  consideration,  of  course 
the  first  question  is  whether  the  new  machinery  is  to  go  into 
an  old  building,  or  whether  it  is  to  be  a  part  of  an  entirely  new 
plant,  buildings  and  all.  And  this  thought  naturally  enough 
leads  directly  up  to  the  further  question  of  foundations.  And 
in  the  consideration  of  foundations  for  the  support  and  anchor- 
age of  pumping  machinery,  especially  for  the  larger  sizes,  it  is 
very  difficult  to  establish  any  fixed  and  exact  rules.  Many 
attempts  have  been  made  and  much  time  lost  in  endeavoring 
to  establish  some  sort  of  formula  for  reaching  satisfactory 
results;  but  there  are  so  many  changing  circumstances,  varia- 
tions in  conditions,  and  incidental  things  to  be  taken  into  the 
account,  that  it  is  difficult  to  see  how  the  question  can  have 
any  theoretical  side  at  all. 

The  only  principle  of  material  value  is  the  one  which  involves 
the  loading  of  the  foundation,  expressed  in  pounds  pressure 
per  square  foot  upon  its  bed,  so  as  to  keep  within  a  safe  work- 
ing limit.  And  in  the  matter  of  load  upon  the  foundation  bed, 
it  is  extremely  necessary  to  make  the  important  distinction 
between  a  live  load,  such  as  a  working  engine,  and  a  dead  load, 
such  as  the  walls  of  a  building.  It  goes  without  saying,  that  a 
heavy,  strong,  and  suitable  foundation  is  absolutely  necessary 
for  the  best  results,  and  this  is  especially  so  in  the  case  of  pump- 
ing engines.  There  are  all  sorts  of  rules  and  ideas  concerning 
the  spread,  weight,  length,  breadth,  and  depth  of  foundation, 
but  the  situation  and  conditions,  as  in  all  other  matters  per- 
taining to  the  accomplishment  of  any  definite  purpose,  must 

193 


INSTALLATION  OF  PUMPING  ENGINES  199 

largely  govern  the  efforts  in  this  direction.  A  pumping  engine 
comes  under  the  head  of  "live "loads"  upon  a  foundation  as 
opposed  to  anything  which  does  not  of  itself  embody  a  living 
and  moving  force;  and  a  good  general  rule  with  reference  to 
the  foundation  of  a  pumping  engine  is  to  allow  800  Ibs.  to  the 
square  foot  upon  the  bottom  or  upon  the  bed  of  the  founda- 
tion, inclusive  of  the  weight  of  the  foundation  itself,  when 
upon  good  earth  or  soil,  and  this  will  give  enough  area  to  the 
bottom  for  any  good  soil.  With  rock  for  a  bed,  a  less  area  of 
bottom  will  be  sufficient ;  in  fact,  the  least  area  consistent  with 
sufficient  space  to  support  the  machinery  at  the  top  of  the 
foundation  will  answer  all  purposes  with  a  rock  bed;  and  it 
is  only  when  the  work  must  rest  upon  a  bed  of  soil,  clay,  gravel, 
or  other  earthy  materials  in  the  absence  of  rock  bottom,  or 
in  the  case  of  such  extreme  depth  down  to  the  rock,  that  the 
excavation  and  subsequent  filling  with  foundation  materials 
is  very  costly  and  troublesome,  that  the  bearing  pressure  is 
to  be  brought  down  to  what  may  appear  to  some  as  the  low 
figure  of  800  Ibs.  to  the  square  foot  of  area  of  bed. 

Foundations  may  sometimes  be  unnecessarily  expensive  on 
account  of  cut  stone  caps,  anchor  plate  stones,  and  other 
costly  things,  but  it  cannot  be  too  solid.  The  idea  of  a  foun- 
dation for  a  living,  working  engine,  is  to  make  it  as  nearly  as 
practicable,  represent  a  fixed  part  of  the  entire  mass  of  the 
earth  by  its  weight,  spread,  and  bearing;  and  when  this  is 
accomplished  to  the  extent  of  preventing  all  settlements, 
tremor,  or  disarrangement  of  any  kind,  then  the  stability 
and  operation  of  the  machinery  will  be  assured,  so  far  as  its 
installation  and  location  are  concerned. 

Foundations  for  the  smaller  sizes  and  capacities  of  pump- 
ing machinery  are  generally  made  ample;  apparently  because 
the  cost  is  not  very  great  anyway,  or  is  comparatively  small 
and  simple  in  form.  But  as  the  magnitude  of  the  plant  in- 
creases, the  proportions  of  the  smaller  unit  carried  out  in  a 
larger  unit,  seems  to  make  the  dimensions  and  cost  loom  up 
to  an  extent  which  startles  the  designer.  Of  course  the  fact 


200  PUMPING    ENGINES 

is  partly,  perhaps  principally,  that  with  small  machinery, 
say  a  2,000,000  gallon  horizontal  pumping  engine,  just  a  mono- 
lith or  solid  mass  of  masonry  of  the  required  length  and  breadth, 
and  perhaps  3  or  at  the  most  4  feet  deep,  will  make  a  proper 
foundation,  and  in  such  cases  the  weight  per  square  foot  of 
bed  is  very  much  less  than  800  Ibs.  Such  a  small  simple  thing 
as  a  brick  or  concrete  pier  10  feet  long,  5  feet  broad,  and  4  feet 
deep  is  easy  and  inexpensive  to  build,  but  when  it  comes  to 
a  vertical,  triple  expansion  pumping  engine  of  the  highest 
type  and  of  considerable  size,  as,  for  example,  15,000,000 
U.  S.  gallons  capacity,  the  foundation  is  calculated  very  closely; 
many  times  too  closely,  to  the  sorrow  of  the  buyer  at  some 
later  day. 

It  can  be  stated  with  the  certainty  and  authority  of  a  self 
evident  proposition  that  money  invested  in  a  proper  founda- 
tion is  money  well  invested;  and  that  money  kept  out  of  a 
foundation  to  the  extent  of  risking  the  success  of  the  machinery, 
expresses  a  saving  very  badly  misplaced.  In  fact  if  the  ques- 
tion must  be  settled  between  apparent  extravagance  and  mis- 
placed economy,  then  the  extravagant  side  of  the  case  ought 
to  be  favored  in  the  interests  of  safety,  low  repair  accounts, 
and  economy  of  operation.  Each  case  ought  to  be  considered 
and  decided  by  itself,  as  experience  shows  that  no  general 
rule  can  be  followed  on  account  of  the  great  variety  of  under- 
ground and  underwater  conditions,  unknown  and  unseen 
until  actually  dug  down  to  and  exposed.  Foundation  mak- 
ing is  not  quite  so  purely  an  art  as  stone  quarrying,  but  there 
is  not  so  very  much  difference  between  them  as  at  first  might 
be  thought. 

When  a  new  pumping  engine  is  to  be  put  into  a  building 
already  in  existence,  a  very  great  care  is  necessary  to  avoid 
doing  damage  to  the  building,  its  foundations,  and  its  walls; 
it  not  infrequently  being  necessary  to  underpin  the  building 
walls  before  the  engine  foundations  can  be  commenced.  The 
writer  in  his  own  experience  lately,  had  such  a  task  in  hand, 
and  the  first  thing  done  was  to  excavate  a  pit  about  5  feet  in 


INSTALLATION  OF  PUMPING  ENGINES  201 

length  in  line  with  the  wall;  and  this  pit  was  carried  down  to 
the  bottom  of  the  building  foundation  which  was  found  to  rest 
upon  coarse  sand  and  gravel.  It  being  necessary  to  go  still 
deeper  to  accommodate  the  new  engine,  which  was  a  vertical 
triple  expansion  machine  of  15,0.00,000  U.  S.  gallons  daily 
capacity,  this  pit,  5  feet  along  the  wall,  was  continued  on  down 
some  12  feet  below  the  bottom  of  the  building  foundation  until 
rock  and  large  immovable  boulders  were  reached.  The  pit 
was  then  carried  beneath  the  building  foundation  for  its  entire 
thickness,  and  a  bed  of  strong  Portland  concrete  was  laid  3 
feet  in  depth,  and  upon  this  concrete  base  a  pier  of  brick  laid 
in  cement  mortar  was  carried  upwards  to  the  bottom  of  the 
foundation  at  this  point,  thus  completely  underpinning  and 
solidly  supporting  the  building  foundation  and  wall. 

After  this  first  pier  had  been  allowed  to  set  enough  to  make 
certain  of  a  proper  support,  another  pier  was  excavated  for 
and  constructed  the  same  as  and  about  5  feet  from  the  first 
one.  This  process  was  continued  until  20  feet  of  the  walls 
at  both  sides  of  the  building  were  solidly  supported  upon 
these  brick  piers  with  spaces  between  them.  The  spaces  be- 
tween the  new  brick  piers  were  then  excavated  to  the  rock, 
and  brick  piers  were  also  built  in  the  openings  thus  formed, 
resulting  in  a  continuous  new  sub-foundation.  Then  the 
earth  inside  the  building  below  the  basement  floor  was  pro- 
tested by  a  retaining  wall  at  two  places,  extending  across  the 
building  and  down  to  the  rock,  so  that  the  entire  space  extend- 
ing clear  across  the  building  and  some  20  feet  lengthwise  of 
the  building  was  excavated  down  to  rock  and  large  heavy 
immovable  boulders,  upon  which  a  bed  of  concrete  made  a 
substantial  and  highly  satisfactory  bed  for  the  foundation  of 
the  new  pumping  engine.  The  walls  of  this  pumping  station 
above  the  main  floor  had  been  lined  and  finished  with  a  high 
quality  of  white  enameled  brick,  with  very  precisely  pointed 
joints;  and  after  the  foundation  work  had  been  completed, 
including  the  foundation  for  the  pumping  engine,  there  was 
not  the  slightest  trace  of  any  cracks  or  settlement  in  the  finished 


202  PUMPING  ENGINES 

surface  of  these  walls.  Such  work  illustrates  the  bad  policy 
of  loading  down  an  engine  contract,  as  already  mentioned 
in  another  chapter,  with  matters  which  do  not  belong  to  it, 
and  which  the  contractor  should  not  be  made  responsible 
for. 

Still  another,  and  fully  as  good  an  illustration,  is  a  case 
rather  more  difficult  than  the  one  already  cited.  A  large  and 
important  pumping  engine,  happening  to  be  also  of  15,000,000 
U.  S.  gallons  daily  capacity,  although  against  a  considerably 
greater  head,  had  been  contracted  for.  This  engine  was  also 
to  go  into  a  building  already  in  existence  and  so  situated  that 
it  could  not  be  replaced  upon  the  same  premises,  and  therefore 
it  meant  the  saving  of  several  thousand  dollars  to  the  buyer 
if  the  existing  building  could  be  utilized;  only  a  moderate 
amount  of  alterations  being  necessary  in  the  building  itself. 
The  foundations  of  this  building  were  not  any  too  stable  in 
construction,  and  rested  upon  rather  a  hard  limestone  bed 
rock  about  12  feet  below  the  main  or  engine  room  floor.  From 
the  corner  of  the  building  the  rock  surface  extended  at  the 
depth  of  12  feet,  about  level,  in  line  with  one  of  the  walls,  and 
ascended  about  4  inches  to  the  foot  along  the  line  of  the  other 
wall,  these  two  walls  forming  the  90  degree  angle  which  made 
the  corner  of  the  building. 

The  outline  plans  for  the  new  pumping  engine  showed  that 
a  distance  of  16  feet  would  be  required  from  the  level  of  the 
engine  room  floor  to  the  under  side  of  the  sole  plate  beneath 
the  water  end  of  the  vertical  machine;  and  in  addition  to  this, 
it  was  necessary  to  allow  at  least  12  inches  for  concrete  in  level- 
ing up  so  as  to  form  a  sub-foundation.  This  meant  that  the 
new  work  would  extend  down  into  the  rock  5  feet  below  the 
building  foundation  at  one  side,  and  13  feet  below  the  surface 
of  the  rock  near  the  middle  of  the  building  at  the  other  side  of 
the  new  engine.  The  work  to  be  done  was  to  excavate  nearly 
straight  down  into  the  rock  until  a  foundation  bed  was  formed, 
practically  although  roughly  level,  and  17  feet  below  the  engine 
room  floor,  leaving  the  foundations  of  the  building  along  the 


INSTALLATION  OF  PUMPING  ENGINES  203 

walls  forming  the  angle,  standing  within  about  a  foot  of  the 
new  excavation  in  the  rock.  The  building  foundation  being 
of  not  any  too  compact  a  character,  it  was  decided  to  under- 
pin the  building  with  concrete  piers  extending  through  the 
original  foundation  walls  and  placed  directly  beneath  the  wall 
piers  between  the  windows,  the  corner  or  angle  being  taken 
care  of  in  a  very  complete  manner  by  means  of  an  extra  heavy 
concrete  angle  pier. 

After  the  walls  had  been  thoroughly  protected,  the  earth 
was  excavated  down  to  the  rock,  and  retaining  walls  of  con- 
crete were  formed  to  hold  back  the  earth  in  the  other  parts 
of  the  building  where  no  basement  existed;  and  then  the  earth 
covering  the  space  where  the  new  engine  was  to  be  located, 
and  having  dimensions  of  42  feet  by  24  feet,  was  excavated 
and  removed  from  the  building,  leaving  the  rock  exposed  where 
the  new  machinery  was  to  be  placed.  Then  commencing 
near  the  middle  of  this  area  of  exposed  rock,  a  pit  was  formed 
down  into  the  rock  by  very  light  blasting,  barring,  and  pick- 
ing; this  being  gradually  increased  in  size  and  deepened  until 
the  required  depth  was  reached,  the  pit  then  forming  a  space 
at  the  bottom  about  10  feet  square.  These  operations  of 
blasting,  barring,  and  picking  were  continued  around  the  sides 
of  the  pit  until  the  rock  excavation  was  finally  completed 
of  the  size,  shape,  and  depth.  A  bed  of  concrete  was  then 
rammed  into  place  until  a  clean,  true,  and  level  surface  was 
formed  just  the  required  distance  below  the  engine  room  floor 
for  the  accommodation  of  the  water  end  of  the  new  pumping 
engine.  The  holes  for  the  anchor  bolts  were  then  laid  out  and 
drilled  by  diamond  core  drills  to  an  average  depth  of  about 
5  feet,  the  bolts  being  secured  in  the  rock  by  a  well  known 
wedging  device.  (See  Fig.  63.) 

When  an  entirely  new  pumping  station  is  built  and  arranged 
for  pumping  units  of  uniform  size  so  far  at  least  as  floor  space 
is  cqncerned;  or  where  a  station  already  in  existence  is  re- 
vamped upon  lines  of  unit  capacities,  although  future  units 
may  be  of  greater  capacitiy  than  the  first  ones  erected,  it  is 


204 


PUMPING   ENGINES 


Fig.  63.  —  Foundations  on  Bock  inside  of  Pumping  Station. 


INSTALLATION  OF  PUMPING  ENGINES  205 

very  easy  to  provide  for  proper  building  foundations,  engine 
foundations,  pump  wells,  intakes,  screen  chambers,  etc.  But 
to  save  unnecessary  expense  in  the  future,  the  arrangements 
of  building  and  engine  foundations,  together  with  the  lay  out 
of  suction  and  delivery  pipes,  must  be  carefully  thought  out 
and  planned  from  the  start,  even  though  all  of  the  work  is  not 
immediately  gone  into.  There  are  very  few  tasks  more  ex- 
pensive, annoying,  and  risky,  in  proportion  to  usefulness, 
than  the  cutting,  carving,  and  digging  necessary  for  the 
placing  of  new  pumping  machinery  and  its  foundations 
within  a  building  already  crowded  with  machinery,  pipes, 
and  masonry.  This  of  course  at  times  has  to  be  done,  and 
largely  no  doubt  because  the  additions,  improvements,  and 
enlargements  are  mostly  made  in  established  plants  possessing 
limited  available  space.  The  matter  of  economically  pro- 
viding for  the  future  is  not  so  difficult  as  it  may  at  first  seem; 
and  the  unit  system  may  be  so  arranged  that  a  plant,  whether 
large  or  small,  in  pumping  capacity,  could  be  composed  of 
what  might  be  called  compound  units,  or  plant  units.  Having 
compound  units  means  to  place  the  machiiiery  in  groups,  as, 
for  example,  four,  five,  or  six  pumping  engines  or  pumping 
units  in  one  complete  building,  the  building  forming  a  plant 
unit.  Then  when  in  the  future  it  becomes  apparent  that  more 
capacity  is  needed,  instead  of  attempting  to  build  onto  or 
enlarge  an  existing  building,  make  the  plans  for  another  group 
or  plant  unit,  conforming  of  course  to  any  changes  or  im- 
provements which  might  have  been  developed  since  the  last 
plant  unit  was  built. 

In  this  way,  having  some  definite  line  to  work  to  the  matter 
of  future  foundations  and  other  accommodations  for  the 
machinery  could  be  intelligently  provided  for,  although  no  more 
of  the  actual  work  need  be  done  than  the  present  demands 
call  for,  the  main  thing  being  to  look  ahead  and  establish  the 
possibilities  for  future  improvements  which,  when  the  time 
came,  could  be  placed  without  annoyance,  undue  expense, 
or  interruptions  of  the  water  works  service.  It  will  surprise 


206  PUMPING  ENGINES 

many  to  observe,  after  a  little  study,  how  much  satisfactory 
work  and  planning  can  be  done  in  this  direction. 

A  great  deal  could  be  written  upon  the  subject  of  pump- 
ing engine  foundations,  but  in  the  absence  of  opportunities 
for  laying  down  hard  and  fast  rules  which  would  be  of  practical 
use  for  future  work,  such  writings  would  naturally  have  to  be 
confined  to  work  already  accomplished;  and,  beyond  the  study 
of  materials  and  methods  of  construction  in  particular  cases, 
not  much  real  good  could  be  done.  A  student,  an  engineer, 
or  a  water  works  manager  would  have  to  determine  in  the 
special  cases  met  by  them,  how  far  the  history  or  record  of  work 
already  accomplished  could  be  properly  applied  to  new  cases 
in  hand. 

Where  excavation,  building  new  foundations,  retaining 
walls,  underpinning,  or  similar  work  is  to  be  done,  it  will  be 
necessary  to  ascertain  by  local  conditions  and  evidence  what 
the  character  of  the  earth  or  soil  may  be  for  quite  a  considerable 
depth  about  the  locality.  In  soil,  no  matter  how  durable  it 
may  appear,  even  after  excavations  have  been  made  it  will 
be  well  to  ascertain  by  drill  rods,  drills,  or  augers,  or  other 
means  of  sinking  test  holes,  to  what  depth  a  firm  and  suitable 
foundation  bed  may  be  depended  upon.  Whenever  a  con- 
siderable depth  has  to  be  tested  it  is  very  often  a  good  plan 
to  drive  down  a  piece  of  wrought  iron  pipe,  and,  if  necessary, 
this  pipe  can  be  made  up  of  moderate  lengths  successively 
screwed  together  by  the  ordinary  pipe  couplings  so  as  to 
increase  the  convenience  of  driving.  It  is  not  difficult  or 
uncommon  in  ordinary  soil  to  cheaply  go  to  the  depth  of  40, 
50,  or  even  100  ft.  for  testing  purposes  by  the  use  of  the  above 
mentioned  or  similar  appliances. 

Rock  is  of  course  always  to  be  preferred  for  the  bed  of 
pumping  engine  foundations,  but  as  it  cannot  always  be 
reached  within  a  reasonable  distance,  it  is  extremely  important 
to  determine  what  course  can  be  safely  followed  under  other 
and  less  desirable  circumstances.  For  example,  where  reason- 
ably tough  or  strong  soil  overlies  rock  to  a  depth  of  from  12 


INSTALLATION  OF  PUMPING  ENGINES 


207 


to  15  ft.  below  what  would  be  suitable  for  the  building  founda- 
tions, but  where  it  would  be  preferable  to  have  if  possible  the 
support  of  the  rock  for  the  engine  foundation,  it  is  quite  prac- 
ticable to  excavate  small  circular  or  square  pits  through  the 
soil  and  down  to  the  rock,  these  pits  being  dug  one  at  a  tune 
and  filled  with  concrete  from  the  rock  up  to  the  level  of  the 
building  foundation,  and  enough  of  them  put  into  proper  posi- 
tion for  taking  the  support  of  the  engine  foundation  and  there- 
by transmitting  the  weight  and  pressure  of  the  machinery  and 


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lig.  64.       Engine  Foundations  on  Concrete  Filing. 

its  foundations  directly  to  the  rock  without  interfering  with 
the  stability  of  the  building  walls.  (See  Fig.  64  and  Fig.  65.) 
It  is  quite  practicable  to  follow  this  method,  even  where  the 
soil  is  not  so  very  firm,  by  first  sinking  tubes  or  caissons  made 
of  steel  or  iron  plates,  carried  down  to  the  rock  and  afterwards 
filled  with  concrete.  The  result  of  these  methods,  either  with 
or  without  the  caisson,  is  to  support  the  engine  foundation  upon 
concrete  piles  or  columns,  reinforced  by  earth. 

Such  a  case  is  recalled  to  mind  where  the  pumping  station 
had  to  be  located  about  300  ft.  from  the  river  edge,  and  had 
been  built  for  the  accommodation  of  two  horizontal  engines  with 


208 


PUMPING   ENGINES 


space  left  for  two  more,  the  engine  room  being  oblong  and  the 
engines  placed  crosswise.  The  foundations  for  the  machinery 
had  been  built  upon  the  same  soil  as  the  building  walls,  a  mix- 
ture of  sand  and  gravel.  The  weight  of  the  horizontal  engines 
was  quite  moderate  in  proportion  to  capacity,  but  rather  evenly 
distributed,  and  incidentally  had  the  advantage  of  great  area 
of  foundation  bottom  in  proportion  to  the  weight  of  the 
machinery,  the  weight  upon  the  foundation  bed  not  exceeding 
400  Ibs.  to  the  square  foot.  This  light  load  had  probably  not 
been  sought  for,  but  was  purely  incidental  to  the  shape,  dimen- 


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Fig.  65.  —  Engine  Foundations  on  Concrete  Filing. 

sions,  weight,  and  disposition  of  the  machinery.  These  two 
engines  had  been  in  service  long  enough  to  have  the  gross 
demands  for  water  increase  until  it  very  nearly  equaled  their 
combined  capacity. 

After  it  had  been  decided  to  increase  the  capacity  of  the 
station,  an  investigation  of  all  the  circumstances  resulted  in  a 
recommendation  to  utilize  the  remaining  space  in  the  builcing 
by  putting  in  a  vertical,  triple  expansion,  crank  and  fly-wheel 
engine,  equaling  the  combined  capacity  of  the  two  original 
machines.  Fortunately,  for  architectural  effect,  the  building 
had  been  made  rather  lofty  for  the  accommodation  of  horizontal 


INSTALLATION  OF  PUMPING  ENGINES.  209 

machinery,  so  that  by  going  down  to  a  considerable  depth  foi* 
foundations,  the  proposed  new  vertical  engine  would  just  about 
fit  the  case.  The  floor  in  the  reserve  portion  of  the  building 
was  removed  and  excavation  commenced.  There  was  a  base- 
ment to  the  building,  and  the  foundation  of  the  walls  extended 
a  few  feet  below  the  basement  floor.  It  was  found  by  sounding 
and  boring  that  there  was  bed  rock  about  20  ft.  below  the  base- 
ment floor  and  practically  level  beneath  the  location  of  the  pro- 
posed new  engine,  and  it  was  also  found  that  the  upper  surface 
of  the  lower  flat  portion  of  the  engine  foundations  would  have 
to  be  at  the  level  of  the  bottom  of  the  building  foundations. 

It  was  soon  ascertained  that  the  underpinning  of  the  building 
walls  would  be  pretty  expensive,  and  it  was,  therefore,  decided 
that  4  ft.  would  be  thickness  enough  for  the  bottom  portion  of 
the  engine  foundation,  and  under  the  circumstances  4  ft.  was 
considered  to  be  the  safe  limit  of  depth  to  go  into  the  soil  below 
the  level  of  the  building  foundations.  This  would  leave  about 
11  or  12  ft.  of  soil,  more  or  less  uncertain  in  quality  and  expo- 
sure to  saturation,  between  the  bottom  of  the  engine  foundation 
and  the  rock.  After  looking  the  matter  carefully  over,  the  con- 
clusion was  reached  that  the  best  plan  would  be  to  sink  a 
number  of  wells,  about  4  ft.  square,  down  to  the  rock  and  so 
provide  solid  concrete  supports  between  the  rock  and  the 
bottom  of  the  engine  foundation.  This  was  successfully  carried 
out,  although  in  some  of  the  holes  it  was  necessary  to  place 
sheathings  of  plank  with  cross  bracing,  to  safely  support  the 
soil  while  the  concrete  pillars  or  piling  were  being  rammed  into 
place.  In  all  cases  where  the  sheathing  was  used,  the  brac- 
ing was  taken  out  as  the  level  of  the  concrete  was  brought  up, 
but  in  some  of  the  holes  it  was  found  necessary  to  leave  the 
planking  in  place.  The  4  ft.  of  depth  between  the  top  of  the 
concrete  piling  and  the  bottom  of  the  building  foundations  was 
protected  at  the  sides  by  planking  and  bracing  until  the  bed  of 
concrete  was  safely  rammed  into  place.  The  planking  around 
these  sides  having  been  placed  vertically,  was  easily  removed, 
and  the  soil  was  thoroughly  compacted  against  the  sides  of  the 


210  PUMPING  ENGINES 

concrete.  Upon  this  platen  or  cake  of  concrete,  36  ft.  long, 
20  ft.  broad,  and  4  ft.  thick,  forming  a  large  artificial  stone, 
solidly  supported  from  the  rock  and  with  its  upper  surface  at 
the  level  of  the  bottom  of  the  building  foundations,  the  pier 
for  supporting  one  end  of  the  engine  bedplate  at  the  floor  level 
was  built.  The  new  engine,  of  12,000,000  U.  S.  gallons  capacity 
against  200  feet  head,  was  erected  in  place  and  put  into  service 
without  any  evidence  of  cracking  or  settlement  of  the  masonry 
appearing  after  the  lapse  of  nearly  a  year,  and  it  is  presumed 
that  the  future  will  show  equally  as  well. 

Sometimes  situations  are  met  with  where  a  yielding  soil  is 
found  to  overlie  firm  gravel,  hard  compact  sand,  hard  pan  or 
rock  with  the  upper  material  too  deep  to  permit  of  excavation 
down  to  the  firm  material  or  to  carry  down  concrete  columns 
as  already  referred  to.  In  such  cases  timber  piling  may  be 
resorted  to  with  success,  provided  the  harder  material  can  be 
reached  by  the  lower  ends  of  the  piling,  and  through  such 
supports,  aided  by  the  compacted  earth  around  the  piles,  a  satis- 
factory foundation  may  be  secured.  But  where  the  soft  mate- 
rial is  so  deep  that  a  hard  bottom  cannot  be  reached  by  the 
lower  ends  of  the  piles  nothing  but  the  most  urgent  necessities 
should  permit  the  location  of  pumping  machinery  in  such  a 
place.  Of  course  the  compacting  of  the  soft  earth  between  the 
piles  will  take  place,  and  a  comparatively  homogeneous  mass 
will  result,  but  though  the  individual  piles  will  be  little  liable 
to  sink,  the  entire  mass  as  a  whole  will  be  likely  to  settle  in  the 
course  of  time.  This  may  not  be  particularly  injurious  to  a 
building  or  to  a  dead  load,  but  entails  a  good  many  risks  to  a 
-live  moving  load,  like  a  pumping  or  a  power  engine,  risks  which 
had  better  not  be  taken.  Such  things  are  occasionally  done, 
but  they  are  strongly  advised  against. 

If  piling  must  be  resorted  to,  the  situation  of  the  machinery 
in  a  particular  spot  making  such  a  location  very  important, 
and  the  use  of  piling  a  secondary  matter,  especially  if  a  hard 
bottom  can  be  reached  by  the  lower  ends  of  the  piles,  these 
should  be  placed  ordinarily  with  about  2\  times  the  diameter 


INSTALLATION  OF  PUMPING  ENGINES  211 

of  the  pile  between  centers.  The  tops  should  be  sawed  off 
to  a  uniform  elevation,  and,  if  necessary,  capped  with  a  grill 
work  of  timber,  some  arrangement  of  heavy  planking  or  other 
device  deemed  best  for  the  situation,  although  too  much  tim- 
ber work  should  be  avoided  on  account  of  the  changes  which 
more  or  less  dryness  or  dampness  of  wood  may  occasion;  it 
being  remembered  that  these  changes  come  laterally,  but  as 
a  rule  not  at  all  lengthwise  of  the  timber.  Then  a  bed  of  con- 
crete from  3  to  6  ft.  in  thickness,  covering  the  entire  surface 
of  the  tops  of  the  piling  and  the  timber,  will  provide  a  sub- 
stantial bed  upon  which  to  build  the  engine  foundation.  Some- 
times where  the  conditions  permit,  concrete  is  placed  over 
and  around  the  heads  of  the  piling  without  the  intervention 
of  the  grill  work  or  planking,  and,  where  possible,  this  method 
is  to  be  preferred  on  account  of  the  absence  of  chances  for 
cross  shrinkage  of  the  timbering. 

Of  course  the  walls  of  the  building  should  be  firmly  supported 
upon  piles,  if  necessary,  but  independently  of  the  foundation 
bed  for  the  machinery.  No  special  rules  or  directions  can  be 
safely  given  for  such  work,  for  the  simple  reason  that  when 
the  situation  demands  such  treatment  of  a  foundation,  this 
is  evidence  enough  that  each  case  should  be  considered  by 
itself.  The  conditions  are  too  variable  and  uncertain  for 
hasty  conclusions  in  the  absence  of  a  full  knowledge  of  all 
the  facts.  The  safe  load  upon  piles  of  12  inches  diameter  at 
the  top,  when  driven  in  firm  soil  and  without  the  bottom  rest- 
ing upon  hard  pan  or  rock,  should  not  be  reckoned  at  more 
than  15  to  18  tons  per  pile,  with  a  dead  load,  and  not  more 
than  8  tons  with  a  live  load,  like  a  steam  engine  at  work. 

Authorities  differ  as  to  the  safe  load  that  may  be  placed 
upon  earth  foundation  beds,  and  give  all  the  way  from  1  ton 
to  4  tons  per  square  foot,  but  mostly  still  loads  are  referred  to. 
So  far  as  the  writer  is  concerned  however,  where  permanent 
and  lasting  results  are  looked  for,  with  smooth  and  economical 
working  pumping  engines,  the  limit  is  put  at  1,000  Ibs.  per 
sq.  ft.,  and  preferably  800  Ibs.  for  the  machinery,  and  3,000 


212  PUMPING  ENGINES 

Ibs.  for  the  building  walls  of  the  pumping  station,  when  the 
bed  is  the  best  of  earth.  An  equally  distributed  pressure  is 
to  be  carefully  sought  after  and,  in  the  absence  of  a  rock  bed 
or  its  equivalent,  it  is  well  worth  the  while  to  pay  particular 
attention  to  the  uniform  distribution  of  the  pressure. 

As  to  the  matter  of  material  for  engine  foundations,  after 
the  question  of  bed  has  been  properly  decided,  a  concrete 
bottom,  then  the  foundation  piers  of  hard  burned  brick,  with 
granite,  limestone,  or  hard  sandstone  anchor  bolt  stones  and 
cap  stones  will  give  as  good  results  as  any,  and  better  than 
most  other  materials  or  combination  of  materials.  There 
is  a  great  advantage  in  brickwork  because  brickwork  can  be 
laid  up  closely,  and  true  to  the  required  form,  with  full  mortar 
beds  and  joints.  This  material  will  knit  together  and  make 
a  very  manageable  and  practical  construction;  and  when  good 
hard  brick  is  laid  in  Portland  mortar  of  proper  richness,  not 
too  rich,  say  1  cement  and  2  of  sand,  there  is  nothing  more 
to  be  desired  in  the  way  of  solidity. 

It  is  not  absolutely  necessary  to  use  cap  stones,  although  a 
better  piece  of  work  can  be  done  when  cap  stones  are  used, 
but  there  should  be  something  in  the  line  of  washer  stones 
where  pockets  for  the  bottom  ends  of  anchor  bolts  are  arranged 
to  be  gotten  at  when  desired.  But  a  brick  foundation  can  be 
built  and  finished  off  smooth  enough  on  top  for  the  setting 
of  machinery,  if  the  cap  stones  are  considered  as  adding  too 
much  to  the  cost  of  the  work.  In  this  case  the  heavy  castings 
would  be  leveled  up  correctly,  and  then  cement  and  sand  grout 
run  under  them.  A  thin  mortar  of  3  parts  cement  and  1 
part  sand  will  make  a  very  satisfactory  grout  and  it  should 
be  made  pretty  rich  with  cement  to  make  certain  of  its  running 
properly  under  the  castings.  There  should  be  a  liberal  space, 
say  2  inches,  between  the  castings  and  the  brickwork  so  as 
to  make  a  solid  bed  of  grout  and  avoid  all  chances  of  the 
space  not  filling,  as  would  likely  be  the  case  if  a  thin  sheet 
of  grout  should  be  attempted.  If  the  grout  is  not  pretty 
rich,  say  3  cement  and  1  sand,  it  will  not  flow  well,  because 


INSTALLATION  OF  PUMPING  ENGINES  213 

the  cement  will  take  up  and  follow  the  water,  while  if  there 
be  too  much  sand  in  the  grout,  it  will  settle  before  the  mixture 
reaches  well  under  a  large  casting.  Probably  4  ft.  is  about 
the  limit  to  which  grout  can  be  properly  run  from  any  one 
point;  so  where  it  is  known  beforehand  that  grout  is  to  be 
used,  provisions  should  be  made  for  pouring  from  several 
places  about  the  casting.  The  writer  observed  recently  where 
some  large  horizontal  engines  were  being  bedded,  on  top  of 
brick  foundations,  that  rather  heavy  cement  mortar  was  being 
rammed  and  packed  beneath  the  castings  by  means  of  wooden 
paddles,  the  castings  being  supported  the  meanwhile  upon 
wedges;  the  space  underneath  these  castings  was  about  1-| 
inches  and  the  work  seemed  to  be  progressing  in  a  very  satis- 
factory manner. 

The  matter  of  concrete  is  a  very  important  one,  and  a  strong 
compact  mixture  should  be  made  for  engine  foundations, 
whether  the  entire  foundation  is  made  of  concrete,  as  is  some- 
times done,  or  whether  the  lower  part  or  bed  only  is  formed  of 
this  material.  The  best  working  mixture  for  concrete  for  foun- 
dations or  for  work  about  water,  such  as  core  walls,  and  similar 
work  pertaining  to  dams,  reservoirs,  gate  houses,  etc.,  is  in  the 
writer's  opinion  1  part  Portland  cement,  2  parts  sand,  and 
4  parts  crushed  stone.  Such  a  mixture  will  fill  the  voids  com- 
pletely and  make  a  close  grained,  solid  artificial  stone  as  may 
be  seen  from  the  following  : 

If  a  wooden  box  is  made,  of  one  cubic  yard  in  measurement, 
or  36  inches  long,  broad,  and  deep,  its  cubical  contents  will 
be  36  X  36  X  36,  equal  to  46,656  cubic  inches.  And  if  a  perfect 
globe  of  stone  with  a  diameter  of  36  inches  is  placed  in  such  a 
box,  of  course  it  would  touch  the  top,  bottom,  and  the  four 
sides.  The  cubical  contents  of  the  globe  would  be  the  cube 
of  the  diameter  multiplied  by  the  decimal  0.5236,  or  it  would 
be  36  X  36  X  36  X  0.5236,  equal  to  24,429  cubic  inches.  The 
empty  space  will  then  be  the  difference  between  these  two 
quantities,  or  nearly  48  per  cent  or  say  practically  one  half 
solid  and  one  half  space  or  void. 


214  PUMPING   ENGINES 

If  globes  3  inches  in  diameter  were  placed  in  the  box,  there 
will  be  12  globes  each  way  for  12  layers,  or  12  X  12  X  12,  equal 
to  1,728  of  the  3  inch  globes.  The  cubical  contents  of  one 
of  the  3  inch  globes  would  be  3  X  3  X  3  X  0.5236  or  14.1372 
cubic  inches,  which  multiplied  by  the  number  of  3  inch  globes, 
1,728,  will  give  24,429  cubic  inches  or  the  same  as  with  the 
single  globe  of  36  inches  diameter.  This  of  course  means  that, 
whatever  the  size  of  the  globes,  the  result  will  be  that  there 
will  be  practically  half  solid. and  half  space  or  voids. 

Crushed  stone  is  not  as  regular  as  the  globes  just  referred 
to,  but  the  irregularities  amount  to  about  the  same  thing, 
fitting  together  in  some  places  and  holding  apart  in  others, 
so  that  take  it  altogether  the  rule  of  half  solids  and  half  voids 
will  hold  good.  Therefore  when  the  cubic  yard  box  is  filled 
with  crushed  stone,  there  will  be  room  for  half  a  cubic  yard 
of  sand  in  the  spaces  between  the  stones;  and  again,  after  the 
sand  is  in  place,  there  will  be  room  for  half  as  much  cement  in 
the  spaces  between  the  sand  grains,  or  a  quarter  of  a  cubic 
yard  for  cement.  As  8  ordinary  cement  barrels  full  of  crushed 
stone  will  make  a  cubic  yard,  there  will  be  4  barrels  of  sand 
and  2  barrels  of  cement  in  the  mixture,  or  2  cement,  4  sand, 
and  8  stone;  or,  as  at  first  given,  1-2-4  for  the  best  and  strongest 
mixture  for  concrete.  This  cannot  be  carried  out  as  exactly 
as  the  globes  indicate,  but  the  barrel  measurement  given  above 
will  answer  all  practical  purposes. 

To- show  how  closely  the  sand  will  follow  the  same  law  as  the 
crushed  stone,  it  may  be  assumed  for  the  purpose  of  calcu- 
lation that  the  sand  grains  are  globes  one  fiftieth,  0.02,  of  an 
inch  in  diameter;  then  0.02  X  0.02  X  0.02  X  0.5236  will  equal 
0.0000041888  of  a  cubic  inch  as  the  cubical  contents  of  a  grain  of 
sand.  At  one  fiftieth  of  an  inch  diameter  there  will  be  1,800 
grains  each  way  in  the  36  inch  box,  which  will  make  1,800  X 
1,800  X  1,800  or  5,832,000,000,  which  multiplied  by  the  cubical 
contents  of  each  grain  will  give  24,429  cubic  inches,  as  before, 
as  the  solid  contents  of  a  cubic  yard  of  sand,  leaving  about 
half  a  cubic  yard  as  voids  if  the  box  contained  only  sand. 


INSTALLATION  OF  PUMPING  ENGINES  215 

Engine  foundations  arc  sometimes  built  of  stone,  but  un- 
less of  cut  stone  or  at  least  of  dressed  stone  with  true  beds  and 
joints,  this  material  is  nothing  like  so  good  as  brick.  Rubble 
stone  for  such  work  is  very  objectionable,  unless  a  good  deal 
of  dressing  of  the  stone  is  done,  and  this  would  not  pay  in  the 
absence  of  very  cheap  material.  Rough,  thick  beds  and  joints 
in  a  foundation  for  supporting  a  live  load  are  not  to  be  com- 
mended at  all;  they  are  likely  to  lead  to  trouble  with  the 
machinery.  Rubble  work  when  put  in  with  reference  to  core 
walls  and  like  work,  where  it  can  be  made  water  tight  but 
practically  supporting  no  load  to  speak  of,  is  very  acceptable; 
but  for  pumping  engine  foundations  it  should  be  avoided. 

Concrete  foundations  are  coming  more  and  more  into  use, 
and  some  very  well  appearing  work  has  been  done  in  this 
line,  although  for  general  work,  if  the  truth  were  known,  when 
proper  materials  and  mixtures  are  employed,  the  cost  of  forms 
is  considered,  etc.,  the  price  per  cubic  yard  will  go  above  brick- 
work trimmed  with  stone,  and  would  be  a  useless  expense. 
There  has  been  a  sort  of  fad  on  concrete  of  late  years,  but  it 
will  eventually  settle  into  its  proper  place  and  like  all  other 
good  things  play  its  allotted  part  of  usefulness.  It  is  ex- 
cellent for  subfoundations  where  no  special  or  exact  form  is 
needed,  and  where  it  can  be  rammed  into  place  and  brought 
up  to  some  general  level,  to  build  the  regular  foundation  upon; 
but  is  not  desirable  for  the  upper  work  in  important  plants 
unless  special  reasons  exist  for  its  use. 

Large,  vertical,  self  contained  pumping  engines  resting  upon 
a  bottom  or  sole  plate,  extending  beneath  the  entire  machine, 
need  nothing  more  than  a  flat  layer  of  concrete  underneath, 
although  the  concrete  should  be  bedded  on  rock  or  have  some 
equivalent  support;  and  in  such  a  situation  there  is  probably 
nothing  better  than  concrete,  and  considering  the  difficulties 
often  met  with  in  the  lower  parts  of  such  work,  possibly  it 
is  the  least  costly  construction  that  can  be  employed. 


CHAPTER  XVI 
INVESTMENT    VALUE   OF  PUMPING    ENGINES 

THESE  tables  exhibiting  the  investment  value  of  pumping 
plants  containing  various  types  and  classes  of  pumping  engines 
with  adequate  boilers,  are  based  upon  data  which  are  consid- 
ered to  be  such  as  will  show  practical  conditions  in  the  average 
run  of  plants  in  actual  use  in  water  works  service.  Of  course 
it  is  impossible  to  make  a  schedule  which  will  hit  all  plants; 
but  the  water  pressure  given  will  be  found  to  be  a  safe  basis 
for  calculations,  and  although  a  little  higher  or  a  little  lower 
pressure  will  vary  the  actual  figures  for  power  and  fuel,  the 
relations  will  not  change  much  under  the  same  conditions.  It 
will  be  safer  to  consider  any  particular  case  by  itself,  but 
the  tables  will  indicate  closely  approximate  results.  The  data 
of  the  tables  are  as  follows: 

Number  of  days  for  a  year's  work 365 

Number  of  hours  of  pumping  each  day 16 

Number  of  watches  each  day 2 

Length  of  watches  in  hours      8 

Pay  of  operating  engineers  per  year $1,200 

Pay  of  firemen  per  year 600 

Pay  of  extra  men  per  year 600 

Maintenance  account  of  engines       3% 

Interest  account  of  engines 4% 

Sinking  fund  for  vertical  triple  engines       3% 

Sinking  fund  for  all  other  types  of  engines 5% 

Oil,  waste,  packing,  and  small  repairs 1% 

The  calculations  in  the  following  tables  are  based  upon  a 
fair  average  price  for  machinery,  foundations,  and  appurte- 
nances, together  with  boilers  and  their  appliances.  Also  upon 
'an  actual  evaporation  in  the  boilers  of  8  Ibs.  of  steam  pro- 
duced at  the  working  pressure  with  one  pound  of  coal;  also 

216 


f 
INVESTMENT  VALUE  OF  PUMPING  ENGINES       217 

'upon  a  price  paid  for  the  coal  of  $3  per  net  ton  of  2,000  Ibs. 
in  the  fire  room  ready  for  firing;  also  upon  a  total  water  load 
upon  the  plungers  of  90  Ibs.  per  square  inch,  or  a  total  work- 
ing head  of  207  ft.,  including  suction  and  friction  of  the  water. 

The  desire  is  frequently  expressed  by  interested  parties; 
for  a  sort  of  schedule  or  rate  of  cost  or  price  of  pumping  engines ; 
but  it  is  a  very  difficult  matter  to  make  a  list  of  such  costs 
which  at  any  certain  time  will  be  reliable  beyond  an  approxi- 
mate guide  for  estimation.  In  fact  all  prices  pertaining  to 
specially  defined  contracts  are  more  or  less  fickle  and  change- 
able. About  January,  1899,  prices  of  all  sorts  of  materials 
began  to  rise,  and  by  1901  were  at  a  point  higher  than  for  sev- 
eral years.  In  the  spring  of  1904,  a  downward  tendency  devel- 
oped and  coke  ovens  in  western  Pennsylvania  were  shut  down, 
pig  iron  began  to  decline,  Portland  cement  fell  decidedly  oft0 
in  price,  steel  products  were  lower,  cast  iron  water  pipe  was 
at  $23  per  ton,  and  a  general  fall  in  prices  threatened.  But 
by  the  autumn  of  the  same  year  (1904)  the  drooping  markets 
again  strengthened  and  have  advanced  steadily  since,  until 
now,  January,  1907,  cast  iron  pipe  is  above  $30  per  ton,  steel 
products  are  high  and  hard  to  get,  and  orders  are  booked  for 
a  year  ahead. 

In  1900  the  city  of  Cleveland  rejected  all  bids  for  pumping 
machinery  at  an  attempted  letting  at  that  time,  because  the 
prices  asked  were  so  high  as  to  seem  prohibitive ;  and  the  needed 
machinery  was  bought  two  years  later  at  better  figures  for  the 
city. 

Based  upon  the  low  figures  of  1896,  the  writer  has  a  record 
of  bids  on  pumping  engines  per  million  gallons,  varying  from 
the  bottom  upwards,  as  follows: 

A.  Bottom  figures  of  1896,  represented  by 100% 

B.  Later  figures 137% 

C.  Still  later  figures      118% 

D.  Comparatively  recent  figures 155% 

So  it  will  be  observed  that  about  the  best  attempt  can  only 
result  in  a  fair  average  "subject  to  change  without  notice/1 


218 


PUMPING  ENGINES 


according  to  the  labor  and  material  markets,  and  also  depend- 
ing upon  the  state  of  the  shops  bidding  upon  the  special  work 
in  question.  When  a  shop  is  "hungry  for  work"  bids  will  be 
low;  and  when  the  shop  is  "full  up  with  work"  bids  will  be 
high.  All  shops  do  not  strike  the  tide  at  the  same  stage  at 
the  same  time,  and  hence  a  certain  amount  of  "irregularity" 
in  the  market  with  a  strong  or  a  weak  undertone  as  the  case 
may  be  according  to  the  time. 

A  fairly  good  guide  for  complete  plants  is  given  herewith 
which  is  sufficiently  close  for  preliminary  estimates,  but  con- 
ditions should  be  looked  into  carefully  for  exact  estimates. 
In  some  actual  cases  these  figures  may  be  a  little  too  high 
and  in  other  cases  too  low;  but  they  are  closely  approximate 
and  enough  of  them  are  based  upon  records  to  fairly  insure 
the  table  as  safe  for  practical  use.  In  fact,  the  table  is  so 
close  that  it  would  be  taking  chances  for  a  contractor  to  guar- 
antee the  production  of  results  for  the  figures  named,  without 
investigating  each  case  by  itself.  The  work  contemplated  is 
for  the  best  type  of  triple  expansion  pumping  engines  and 
high  pressure  boilers,  a  good  design  and  quality  of  brick  build- 
ings, or  of  stone  where  stone  is  cheap,  steel  trussed  arid  slate 
covered  roofs,  adequate  chimneys,  properly  proportioned  and 
thoroughly  screened  intakes.  The  cost  given  includes  every- 
thing excepting  the  land. 

Cost  of  complete  pumping  stations. 


POUNDS  PRESSURE 

COST  PER  MILLION 

PER  SQUARE  INCH  OF 

GALLONS  OF  PLANT  CA- 

THE WATER  LOAD 

PACITY,  INCLUDING 

WORKED  AGAINST. 

A  RESERVE. 

30 

$  6,750 

40 

7,000 

50 

7,250 

60 

7,500 

70 

7,750 

80 

8,000 

90 

8,250 

100 

8,500 

110 

8,750 

120 

9,000 

130 

10,000 

INVESTMENT   VALUE  OF  PUMPING  ENGINES      219 

There  are  cheaper  types  of  pumping  engines,  but  they  are 
necessarily  of  lower  efficiency,  and  therefore  requiring  more 
boiler  capacity,  more  coal  storage,  and  other  incidentals  which, 
when  balanced  up,  will  tend  to  keep  the  figures  about  the  same. 
A  cheaper  and  less  durable  sort  of  building  may  be  used,  but 
in  the  long  run  this  will  call  for  more  repairs,  which  when  capi- 
talized will  bring  the  account  fully  back  to  the  above  figures, 
and  most  likely  exceed  them. 

The  following  series  of  tables  show  the  cost  of  installation, 
maintenance,  operation,  repairs,  etc.,  of  pumping  engines  com- 
plete with  piping,  foundations,  appurtenances,  etc.,  within  the 
engine  room  ready  for  continuous  operation  in  service.  Also 
the  cost  of  the  necessary  boiler  plant  within  the  boiler  house, 
including  stokers,  setting,  feed  pumps,  all  piping  and  appur- 
tenances complete.  The  figures  do  not  include  anything  for 
buildings,  land,  chimneys,  wells,  etc. 


Cost   of  pumping  engines  complete,  with  foundations,  piping,  and  appur- 
tenances, per  million  gallons  per  24  hours  capacity. 

Compound  condensing,  low  duty $2,300 

Low  duty  triple  condensing 2,800 

High  duty,  compound  horizontal,  condensing 3,300 

High  duty,  vertical  triple,  condensing 4,800 

Cost  of  boilers   with   stokers,  setting,  feed  pumps,  and   appurtenances 

complete. 

Per  boiler  horse  power $20 

Maintenance  account  of  boilers 5% 

Interest  account  of  boilers 4% 

Sinking  fund  of  boilers      5% 


220 


PUMPING  ENGINES 


Table  showing  the  capacity  per  24  hours,  duty  per  1,000  Ibs.  of  steam, 
steam  consumed  per  hour,  number  of  running  engineers,  firemen,  and 
extra  men,  and  boiler  horse  power. 


Compound  Condensing  Low  Duty   Pumping   Engines. 

MILLION  GAL- 
LONS CAPACITY 

PER 

24  HOURS. 

DUTY  IN 
FOOT  POUNDS 

PER  1,000 

POUNDS  OF 
STEAM. 

POUNDS  OF 
STEAM  CON- 
SUMED PER 
HOUR. 

NUMBER 

OF 

RUNNING 
ENGI- 
NEERS. 

FIRE- 
MEN. 

EXTRA 
MEN. 

REQUIRED 
BOILER 
HORSE 
POWER. 

3,000,000 

50,000,000 

4,276 

2 

2 

0 

150 

4,000,000 

55,000,000 

5,184 

2 

2 

0 

175 

5,000,000 

60,000,000 

5,940 

2 

2 

0 

200 

6,000,000 

60,000,000 

7,128 

2 

2 

0 

250 

7,000,000 

65,000,000 

7,676 

2 

2 

0 

275 

8,000,000 

65,000,000 

8,772 

2 

2 

0 

300 

10,000,000 

65,000,000 

10,966 

2 

2 

0 

375 

12,000,000 

70,000,000 

12,269 

2 

4 

0 

400 

15,000,000 

70,000,000 

15,336 

2 

4 

0 

500 

Triple  Condensing  Low  Duty   Pumping  Engines. 

3,000,000 

75,000,000 

2,851 

2 

2 

0 

100 

4,000,000 

80,000,000 

3,564 

2 

2 

0 

125 

5,000,000 

85,000,000 

4,194 

2 

2 

0 

150 

6,000,000 

95,000,000 

4,752 

2 

2 

0 

175 

Compound  Condensing    High  Duty   Pumping  Engines. 

5,000,000 

110,000,000 

3,240 

2 

2 

0 

100 

6,000,000 

112,000,000 

3,819 

2 

2 

0 

125 

7,000,000 

114,000,000 

4,337 

2 

2 

0 

150 

8,000,000 

116,000,000 

4,916 

2 

2 

0 

175 

10,000,000 

119,000,000 

5,990 

2 

2 

0 

200 

12,000,000 

122,000,000 

7,011 

2 

2 

0 

250 

15,000,000 

125,000,000 

8,554 

2 

2 

0 

300 

Triple  Condensing   High  Duty   Pumping  Engines. 

6,000,000 

140,000,000 

3,050 

2 

2 

0 

100 

7,000,000 

145,000,000 

3,442 

2 

2 

0 

125 

8,000,000 

150,000,000 

3,802 

2 

2 

0 

125 

10,000,000 

155,000,000 

4,597 

2 

2 

0 

150 

12,000,000 

160,000,000 

5,348 

2 

2 

0 

175 

15,000,000 

165,000,000 

6,480 

2 

2 

0 

200 

20,000,000 

170,000,000 

8,388 

2 

2 

2 

275 

25,000,000 

175,000,000 

10,179 

2 

2 

2 

350 

30,000,000 

180,000,000 

11,880 

2 

4 

2 

400 

f  •  , 

INVESTMENT  VALUE  OF  PUMPING  ENGINES      221 


Cost    of    pumping    plants    including    pumping    engines    and    boilers, 
foundations,    piping,    appurtenances,    etc.      Complete   ready  for   service. 


Compound   Condensing   Low   Duty   Pumping   Engines. 

PUMPING 

BOILERS, 

MILLION  GALLONS  PEK 
24  HOURS. 

MACHINERY, 
FOUNDATIONS 

SETTING, 
PIPING  AND 

TOTAL  COST. 

AND  PIPING. 

APPURTENANCES. 

3,000,000 

$  6,900 

$  3,000 

$  9,900 

4,000,000 

9,200 

3,500 

12,700 

5,000,000 

11,500 

4,000 

15,500 

6,000,000 

13,800 

5,000 

18,800 

7,000,000 

16,100 

5,500 

21,600 

8,000,000 

18,400 

6,000 

24,400 

10,000,000 

23,000 

7,500 

30,500 

12,000,000 

27,600 

8,000 

35,600 

15,000,000 

34,500 

10,000 

44,500 

Triple  Condensing  Low  Duty   Pumping  Engines. 

3,000,000 

$  8,400 

$2,000 

$10,400 

4,000,000 

11,200 

2,400 

13,700 

5,000,000 

14,000 

3,000 

17,000 

6,000,000 

16,800 

3,500 

20,300 

Compound  Condensing    High   Duty   Pumping  Engines. 

5,000,000 

$16,500 

$2,000 

$18,500 

6,000,000 

19,800 

2,500 

22,300 

7,000,000 

23,100 

3,000 

26,100 

8,000,000 

26,400 

3,500 

29,900 

10,000,000 

33,000 

4,000 

37,000 

12,000,000 

39,600 

5,000 

44,600 

15,000,000 

49,500 

6,000 

55,500 

Triple  Condensing    High   Duty   Pumping   Engines. 

6,000,000 

$  28,800 

$2,000 

$  30,800 

7,000,000 

33,600 

2,500 

36,100 

8,000,000 

38,400 

2,500 

40,900 

10,000,000 

48,000 

3,000 

51,000 

12,000,000 

57,600 

3,500 

61,100 

15,000,000 

72,000 

4,000 

76,000 

20,000,000 

96,000 

5,500 

101,500 

25,000,000 

120,000 

7,000 

127,000 

30,000,000 

144,000 

8,000 

152,000 

222 


PUMPING  ENGINES 


Table  showing  cost  of  coal  per  year  for  16  hours  pumping  per  day,  mainte- 
nance, interest,  sinking  fund,  oil,  waste,  packing,  small  repairs,  etc.,  for 
the  pumping  engines,  wages  per  year  for  operating  the  boilers  and  pump- 
ing engines,  and  the  sinking  fund,  maintenance,  and  interest  of  the  boiler 
plant.  The  last  or  right  hand  column  shows  the  cost  of  pumping  per 
million  gallons. 


Compound   Condensing   Low  Duty   Pumping   Engines. 

CAPACITY  OF 
PUMPING  ENGINES 
PER  24  HOURS  IN 
U.  S.  GALLONS. 

COST  OF 
COAL  PER 
YEAR  OF 
365  DAYS. 

MAINTE- 
NANCE, 
INTEREST, 
SINKING 
FUND,  OIL, 
WASTE, 
PACKING, 
ETC. 

WAGES 

PER 

YEAR. 

MAINTE- 
NANCE, 
INTEREST, 
SINKING 
FUND,  OF 
BOILERS. 

COST  OF 
PUMPING 

PER 

MILLION 

(lALLONS. 

3,000,000 
4,000,000 
5,000,000 
6,000,000 
7,000,000 
8,000,000 
10,000,000 
12,000  000 
15,000,000 

$4,687 
5,672 
6,504 
7,807 
8,410 
9,600 
11,913 
13,320 
16,784 

$    897 
1,196 
1,495 
1,794 
2,093 
2,392 
2,990 
3,588 
4,485 

$3,600 
3,600 
3,600 
3,600 
3,600 
3,600 
3,600 
4,8-00 
4,800 

$    420 
490 
560 
700 
770 
840 
1,050 
1,120 
1,400 

$13.15 
11.26 
9.99 
9.52 
8.93 
8.44 
8.07 
7.81 
7.75 

Triple  Condensing  Low  Duty  Pumping  Engines. 

3,000,000 
4,000,000 
5,000,000 
6,000,000 

$3,118 
3,907 
4,590 
5,203 

$1,092 
1,456 
1,820 

2,184 

$3,600 
3,600 
3,600 
3,600 

$280 
350 
420 
490 

$11.08 
9.57 

8.57 
7.85 

Compound  Condensing  High  Duty  Pumping  Engines. 

5,000,000 
6,000,000 
7,000,000 
8,000,000 
10,000,000 
12,000,000 
1  5,000,000 

$3,556 
4,161 
4,800 
5,379 
6,550 
7,665 
9,355 

$2,145 
2,574 
3,003 
3,432 
4,290 
5,148 
6,435 

$3,600 
3,600 
3,600 
3,600 
3,600 
3,600 
3,600 

$280 
350 
420 
490 
560 
700 
840 

$7.85 
7.31 
6.94 
6.62 
6.19 
5.86 
5.75 

Triple  Condensing  High  Duty  Pumping  Engines. 

6,000,000 
7,000,000 
8,000,000 
10,000,000 
12,000,000 
15,000,000 
20,000,000 
25.000,000 
30,000,000 

$3,285 
3,766 
4,161 
5,028 
6,025 
7,096 
9,180 
11,142 
12,999 

$3,168 
3,696 
4,224 
5,280 
6,336 
7,920 
10,560 
13,200 
15.840 

53,600 
3,600 
3,600 
3,600 
3,600 
3,600 
4,800 
4,800 
6,000 

$280 
350 
350 
420 
490 
560 
770 
980 
1,120 

$7.07 
6.70 
6.33 
5.91 
5.64 
5.45 
5.22 
4.95 
4.92 

INVESTMENT  VALUE  OF  PUMPING  ENGINES       223 


Table  showing  opposite  the  rated  capacity  of  the  different  engines,  the 
gallons  which  would  be  pumped  per  year  at  full  speed  and  constant 
pumpage.  Also  showing  the  gallons  per  year  with  a  pumpage  of  16 
hours  per  day.  The  latter  rate  taken  as  a  fairly  good  average  for 
water  works  plants.  The  figures  show  U.  S.  gallons. 


CAPACITY  OF  THE 
PUMPING  ENGINES  PER 

CAPACITY  OF  THE  PUMPING 
ENGINES  PER  YEAR 
WORKING  24  HOURS 

CAPACITY  OF  THE  PUMPING 
ENGINES  PER  YEAR, 
WORKING  16  HOURS 

24  HOURS. 

PER  DAY. 

PER  DAY. 

3,000,000 

1,095,000,000 

730,000,000 

4,000,000 

1,460,000,000 

973,000,000 

5,000,000 

1,825,000,000 

1,217,000,000 

6,000,000 

2,190',000,000 

1,460,000,000 

7,000,000 

2,555,000,000 

1,703,000,000 

8,000,000 

2,920,000,000 

1,947,000,000 

10,000,000 

3,650,000  000 

2,423,000,000 

12,000,000 

4,380,000,000 

2,920,000,000 

15,000,000 

5,275,000,000 

3,517,000,000 

20,000,000 

7,300,000,000 

4,868,000,000 

25,000,000 

9,125,000,000 

6,083,000,000 

30.000,000 

10,950,000,000 

7,300,000,000 

The  first  thing  noticeable  in  these  tables  is  that  the  cost  of 
pumping  per  million  gallons,  all  expenses  included,  gradually 
decreases  from  the  smallest  engine  of  the  low  duty  compound 
condensing  class,  to  the  largest  of  the  high  duty  triple  expan- 
sion class.  And  this  decrease  is  brought  about  partly  by  the 
gradual  increase  in  economic  duty  and  partly  by  the  increase 
in  capacity;  some  of  the  charges  per  million  gallons  being 
directly  affected  by  the  increase  in  capacity,  as,  for  example,  a 
5,000,000  gallon  engine  requires  practically  as  much  per  annum 
for  the  wages  of  the  men  as  a  10,000,000  gallon  engine ;  and,  of 
course,  twice  the  water  is  pumped  with  the  latter  as  with  the 
former  which  cuts  the  expense  for  wages  in  halves,  per  million 
gallons.  And,  further,  a  higher  duty  reduces  the  coal  account 
and  the  fixed  charges  against  the  boiler  plant  per  million  gallons. 

But  the  cost  per  million  gallons  does  not  tell  all  of  the  story. 
Because  the  total  cost  in  money  for  pumping  all  of  the  water 
per  annum,  although  lower  per  million  gallons,  may  not  be 
enough  less  total  per  annum,  with  an  engine  of  higher  duty 
and  of  higher  first  cost  to  justify  the  extra  investment.  Plants 


224  PUMPING  ENGINES 

equally  constructed  and  with  equally  low  repair  and  mainte- 
nance accounts,  can  have  no  advantage  over  each  other  except- 
ing in  the  matter  of  fuel  economy;  and  the  lessened  amount  of 
coal  to  be  bought  is  the  real  foundation  upon  which  to  base  an 
increased  investment  in  the  plant.  And,  therefore,  in  con- 
sidering this,  it  will  be  perceived,  as  intimated  above,  that  there 
are  only  two  items  which  grow  less  by  higher  duty,  and  these 
are  the  coal  account  and  the  fixed  charges  on  the  boiler  plant. 
Everything  else  increases  with  higher  duty  excepting  the  wages 
account,  for  equal  capacities,  and  this  account  remains  at 
least  as  much  with  high  as  with  low  duty,  excepting  with  the 
very  large  high  duty  triple  engines,  and  with  these  the  wages 
are  somewhat  less  in  the  fire  room  on  account  of  the  lessened 
amount  of  coal  to  be  shoveled  in  proportion  to  the  pumping. 

The  items  for  and  against  the  high  duty  account  may  be 
tabulated  as  follows: 

Against  High  Duty.  In  Favor  of  High  Duty. 

Maintenance  account  for  machinery.  Maintenance  account  for  boilers. 

Interest  on  machinery.  Interest  on  boilers. 

Sinking  fund  for  machinery.  Sinking  fund  for  boilers. 

Oil,  waste,  packing,  etc.  The  coal  account. 

The  making  of  comparisons  for  the  purpose  of  ascertaining 
before  machinery  and  boilers  are  contracted  for,  which  type 
and  class  it  will  pay  best  to  buy,  requires  comparisons  and  cal- 
culations which  call  for  some  thought  and  care,  but  which  may 
be  readily  enough  made  when  the  actual  conditions  of  the 
contemplated  plant  are  clearly  laid  down.  Of  course  it  goes 
without  saying  that  the  lowest  cost  or  investment  in  a  pumping 
plant  is  the  most  desirable,  all  other  things  being  at  least  equal, 
or  at  least  not  against  the  lower  cost  plant.  This  is  dictated 
by  the  most  ordinary  laws  of  nature  and  common  sense,  which 
insistently  call  for  economy  in  all  things;  but  this  same  natural 
and  insistent  demand  for  economy  is  the  very  spur  which  urges 
us  onward  towards  a  greater  investment  in  a  pumping  plant 
as  well;  but  in  the  case  of  the  plant  of  the  same  capacity  at  a 
higher  cost,  the  economy  takes  the  form  of  economy  in  opera- 


INVESTMENT  VALUE  OF  PUMPING  ENGINES       225 

tion  instead  of  economy  in  first  cost;  the  total  sum  of  all 
expenses  being  less  with  the  plant  of  higher  first  cost.  There- 
fore, the  lowest  investment  or  cost  for  the  plant  being  the  first 
thing  to  consider,  and  the  fact  that  valuable  inducements 
must  be  offered  to  bring  a  higher  cost  plant  into  favor,  it  fol- 
lows that  the  low  duty  engines  must  be  the  basis  for  compari- 
son, and  the  starting  point  for  more  desirable  developments. 

So  far  as  these  tables  are  concerned,  and  the  conditions, 
values,  pressures,  powers,  and  quantities  which  they  set  forth, 
any  plant  costing  more  than  the  regular  low  duty,  compound 
condensing  plants  here  shown,  must  show  itself  capable  of 
saving  enough  money  by  economizing  coal  to  pay  the  different 
items  enumerated,  to  the  extent  represented  by  the  increased 
cost  of  the  higher  duty  and  higher  priced  plant. 

To  illustrate  this  idea  it  may  be  noted  that  the  fixed  charges 
against  the  machinery  and  boilers  are  as  follows : 

Vertical?  Triple  Expansion  Pumping  Engines. 

Maintenance  account 3% 

Interest  account 4% 

Sinking  fund  account 3% 

Oil,  waste,  packing,  and  small  repairs 1% 

Total  fixed  charges 11% 

All  other  types  of  Pumping  Engines. 

Maintenance  account 3% 

Interest  account 4% 

Sinking  fund  account 5% 

Oil,  waste,  packing,  and  small  repairs 1% 

Total  fixed  charges 13% 

NOTE.  —  The  reason  that  there  is  a  difference  of  2  per  cent  made  in 
the  sinking  fund  account,  between  vertical  triple  machinery  and  all 
other  forms,  is  that  it  has  become  evident  that  the  vertical  triple  type  of 
pumping  engine  represents  just  about  the  limit  of  possible  steam  economy, 
and  therefore  the  vertical  triple  type  will  probably  not  be  replaced  as 
obsolete  by  any  of  the  other  types  in  the  tables,  but  the  other  types  will 
eventually  give  way  to  the  vertical  triple  machinery.  Under  these 
circumstances  the  life  of  the  vertical  triple  when  properly  built  is  taken 
at  33 $  years,  and  that  of  all  other  of  the  types  given  at  20  years;  repre- 
senting, respectively,  3  per  cent  and  5  per  cent  to  make  up  the  sinking 
fund  to  100  per  cent  in  the  times  specified. 


226  PUMPING   ENGINES 

The  fixed  charges  against  the  boiler  plant  are  as  follows: 

Maintenance  account 5% 

Interest  account 4% 

Sinking  fund  account 5% 

Total  fixed  charges 14% 

To  make  an  application  of  the  tables  to  an  actual  case,  let  us 
take  for  example  a  6,000,000  gallon  plant,  as  that  capacity 
appears  in  all  of  the  types  and  classes. 

The  total  cost  of  the  different  plants,  including  boilers,  appears 
as  follows: 

Low  duty  compound $18,800 

Low  duty  triple 20,300 

High  duty  compound 22,300 

High  duty  triple 30,800 

The  total  cost  for  operating  per  annum  appears  as  follows: 

Low  duty  compound $13,902 

Low  duty  triple 11,477 

High  duty  compound 10,685 

High  duty  triple 10,333 

Beginning  the  comparison  from  the  low  duty  compound,  up 
to  the  low  duty  triple,  it  is  found  that  the  difference  in  yearly 
cost  of  owning  and  operating  is  2,425  in  favor  of  the  low  duty 
triple;  and  as  the  difference  in  cost  of  plant  is  $1,500,  and 
13  per  cent  (the  fixed  charge)  of  this  difference  amounts  to 
$195,  it  is  clear  that  a  saving  of  $2,425  per  annum  will  justify 
the  use  of  a  low  duty  triple  against  a  low  duty  compound  plant. 

Now  going  still  further  up  the  line,  and  figuring  upon  a  high 
duty  compound,  it  will  be  found  that  the  difference  in  yearly 
cost  between  the  low  duty  triple  and  the  high  duty  compound 
amounts  to  $720  in  favor  of  the  high  duty  compound;  and  as 
the  difference  in  cost  of  plant  is  $2,000,  and  as  13  per  cent  (the 
fixed  charge)  of  this  latter  amount  is  $260,  there  is  a  balance 
of  $502  per  annum  in  favor  of  the  high  duty  compound. 

In  making  the  comparison  directly  between  the  low  duty 
compound  and  the  high  duty  compound,  the  difference  in  cost 


OF  THE 

{    UNIVERSITY  ) 

OF 


INVESTMENT  VALUE  OF  PUMPING  ENGINES     227 

per  annum  and  its  commercial  effect  is  still  more  striking.  The 
difference  in  cost  between  these  two  latter  plants  amounts  to 
$3,500  against  the  high  duty  compound,  but  the  difference 
in  annual  expenses  amounts  to  $3,217  in  favor  of  the  high  duty. 
Then  as  the  fixed  charge  of  13  per  cent  on  the  difference  in 
cost  of  plant  is  only  $455  there  is  a  profit  of  $1,762  per  annum 
between  low  and  high  duty  compound  plants. 

Going  still  further  up,  to  the  high  duty  triple,  it  will  be  found 
that  the  difference  in  yearly  cost  between  the  high  duty  com- 
pound and  the  high  duty  triple  amounts  to  $352  in  favor  of 
the  high  duty  triple.  The  difference  in  cost  of  plants  is  $8,500, 
but  as  the  11  per  cent  (the  fixed  charges  for  high  duty  triples) 
amounts  to  $935,  or  $583  against  the  high  duty  triple  per  annum, 
it  appears  that  with  6,000,000  gallon  engines  against  90  Ibs. 
water  load,  and  with  coal  at  $3  per  net  ton  in  the  fire  room, 
the  high  duty  compound  will  be  the  most  profitable  plant  to 
buy  and  use. 

The  high  duty  triple  would  have  only  $11  per  annum  against 
it  when  compared  with  the  low  duty  triple;  and  the  high  duty 
triple  would  have  $2,249  in  its  favor  per  annum  against  the 
low  duty  compound,  with  the  fixed  charges  of  11  per  cent 
against  the  high  duty  triple. 

Therefore,  under  the  conditions  given  in  the  tables,  the 
6,000,000  gallon  high  duty  triple  with  its  boilers  would  be 
much  preferred  to  the  low  duty  compound;  would  be  just 
about  equal  as  an  investment  to  the  low  duty  triple;  and 
would  not  be  so  good  an  investment  as  the  high  duty  compound. 

A  reduction  in  the  price  of  coal,  but  with  the  coal  equal  in 
quality  to  the  $3  fuel,  the  advantage  would  change  towards 
the  lower  classes  of  engines,  and  with  the  coal  at  a  higher  price 
than  $3  the  changes  would  be  in  favor  of  the  higher  classes 
of  engines. 

The  low  duty  compound  pumping  engines  above  2,000,000  to 
3,000,000  gallons  daily  capacity  have  been  practically  retired 
from  the  water  works  field,  or  should  be  so  far  as  a  desirable 
investment  is  concerned,  and  the  introduction  of  the  low  duty 


228  PUMPING  ENGINES 

triple  has  even  made  the  small  compounds  of  extremely  doubt- 
ful utility  when  any  reasonable  economy  of  investment  and 
operation  is  looked  for.  The  low  duty  triple  in  its  turn  is 
restricted  by  the  high  duty  compound  at  the  5,000,000  or 
6,000,000  gallon  capacity,  and  therefore  the  low  duty  triple  is 
limited  at  6,000,000  in  the  tables.  The  high  duty  compound 
disputes  the  field  with  the  high  duty  triple  from  6,000,000  gallons 
to  10,000,000  gallons  capacity,  according  to  the  cost  of  the  fuel 
used  mostly,  but  also  on  account  of  special  conditions  some- 
times. Above  the  10,000,000  gallon  daily  capacity  it  requires 
especially  adverse  conditions  to  bar  out  the  vertical  triple 
engine  as  the  best  investment  in  machinery  for  pumping  water, 
all  things  considered. 

After  the  10,000,000  gallon  mark  is  passed  the  high  duty 
compound  commences  to  meet  with  difficulties  of  construction 
with  reference  to  making  a  reliable  and  durable  machine  within 
costs  which  do  not  approach  those  of  the  triple  too  closely 
to  justify  its  use.  Also,  the  question  of  extremes  in  low  and 
high  water  involving  suction  lift  and  flood  water,  in  many 
places,  argue  against  large  horizontal  pumping  engines,  it 
being  remembered  that  the  suction  lift  measures  up  to  the  dis- 
charge valve  decks  and  these  become  pretty  high  above  the 
floor  line  in  good  sized  machines ;  also  the  matter  of  more  expen- 
sive building  comes  in  for  consideration,  giving  a  basement 
low  enough  to  enable  the  engine  to  reach  the  water  easily  at 
low  stage,  which  is  by  far  the  most  prevalent  stage,  and  also 
to  have  the  building  so  constructed  that  the  machinery  will 
be  protected  from  the  flood  water  when  the  level  rises.  It 
does  no  special  harm  to  flood  the  water  ends  of  vertical  engines 
so  long  as  the  wheels  are  above  the  water,  but  the  horizontal 
machine  is  brought  to  a  standstill  when  the  water  reaches  the 
steam  cylinders  and  moving  parts. 

The  table  of  high  duty  compounds  is  carried  up  to  15,000,000 
gallon  engines  for  the  purpose  of  making  comparisons,  but 
as  the  vertical  triple  machine  has  been  brought  to  a  commer- 
cial basis  practically,  the  vertical  idea  in  the  compound  involv- 


INVESTMENT  VALUE  OF  PUMPING  ENGINES     229 

ing  as  it  does  more  or  less  special  construction,  places  the  com- 
pound at  a  disadvantage  as  to  cost.  The  cost  of  high  duty 
compounds  given  in  the  tables  refers  to  horizontal  machines, 
and  as  there  are  only  two  standard  engines  of  this  type,  the 
Worthington  and  the  Gaskill,  that  can  be  brought  within  these 
figures  unless  we  go  to  cross  compounds,  which  have  objec- 
tions in  the  large  sizes,  and  further  have  not  been  brought  to 
a  commercial  basis  to  the  degree  represented  by  the  two  above 
mentioned.  There  have  not  been  many  pumping  engines  of 
the  horizontal  type  above  10,000,000  gallons  capacity  built 
in  recent  years,  and  it  looks  as  though  there  would  be  very 
few,  if  any,  so  large  built  in  the  future.  With  coal  at  $3  per 
ton,  the  horizontal  compound  high  duty  engine  can  hold  its 
own  as  an  all  around  investment  against  the  vertical  triple, 
but  the  feeling  against  the  horizontal  class,  with  comparatively 
short  strokes,  and  with  very  large  steam  cylinders  placed  in  a 
horizontal  position,  will  no  doubt  bar  them  out  of  the  larger 
plants. 

Other  forms  of  heat  engines  for  water  works,  in  the  form 
of  the  steam  turbine  pumping  engine,  which  would  likely  con- 
sist of  a  steam  turbine  engine  coupled  directly  to  a  turbine 
pump,  and  also  the  gas  engine  as  a  medium  for  pumping  water, 
begin  to  loom  up  ahead.  But  nothing  definite  has  yet  been 
accomplished  upon  a  scale  large  enough  to  command  respect. 
The  turbine  has  a  very  doubtful  future  before  it,  as  the  pro- 
mises involved  in  the  gas  engine  question  make  the  latter  a 
very  formidable  competitor  at  some  time  in  the  not  very  dis- 
tant future,  even  for  the  present  record  holders. 


CHAPTER  XVII 

SUCTION  LIFT  AND   SUCTION   PIPES 

THE  water  end,  or  the  main  pumps  of  a  water  works  pumping 
engine  and  the  proper  and  efficient  action  of  this  portion  of  the 
machine,  are  the  principal  reasons  for  the  existence  of  the 
apparatus.  The  operation  of  pumping  water  is  extremely 
simpel,  but  there  are  a  few,  very  few,  cardinal  or  main  details 
which  must  be  strictly  observed  if  success  is  to  attend  the 
efforts  of  the  pump  maker.  It  is  pretty  safe  to  say  that,  aside 
from  sufficiently  strong  construction,  the  most  important  detail 
in  the  operation  of  pumping  is  to  get  the  water  into  the  pump 
through  its  suction  valves;  and  for  the  simple  reason  that  the 
force  or  pressure  available  for  that  part  of  the  work  comprised 
in  what  is  called  "suction  lift"  and  the  complete  filling  of  the 
plunger  chambers,  is  very  limited  indeed,  in  fact,  limited  to 
the  comparatively  slight  pressure  of  the  atmospheric  air  which 
we  breathe  in  our  lungs.  A  great  abundance  of  force  is  avail- 
able for  discharge,  or  forcing  the  water  out  of  the  pump,  but 
the  height  to  which  the  water  may  be  "lifted"  above  the  surface 
of  the  well  from  which  it  is  drawn,  and  the  velocity  or  speed 
which  it  can  be  made  to  take  through  the  suction  pipes  and 
pump  valves,  are  absolutely  fixed  and  moderated  by  a  very 
limited  amount  of  force. 

Under  normal  conditions  and  with  the  pump  empty  of  water 
and  at  rest,  the  water  stands  at  the  level  of  th'  well  supply, 
and  the  natural  air  is  in  the  pump  and  well  alike.  But  the 
moment  an  attempt  is  made  to  displace  the  air  within  the 
pump  chambers  and  suction  pipe,  by  the  motion  of  the  plungers, 
or  by  any  other  means  such  as  driving  the  air  out  of  the  pump 
by  means  of  a  steam  or  water  jet,  or  by  any  means  whatever, 

230 


SUCTION  LIFT  AND  SUCTION  PIPES  231 

then  the  natural  pressure  of  the  air  within  the  pump  becomes 
less  than  the  pressure  of  the  outer  air  having  access  to  the  pump 
well,  just  in  proportion  as  the  removal  of  the  air  within  the 
pump  is  carried  to  completion. 

Under  the  ordinary  conditions  of  the  atmosphere  we  breathe 
and  when  the  temperature  is  moderate,  say  from  40  to  90  degrees, 
according  to  the  ordinary  thermometer  we  are  accustomed  to 
see  every  day,  the  pressure  of  the  air  is  about  15  Ibs.  per  square 
inch;  to  be  exact,  with  the  air  at  60  degrees  temperature  at 
sea  level  the  pressure  is  14.7  Ibs.  And,  if  all  of  the  air  is  re- 
moved by  any  means  from  the  inside  of  an  air  tight  vessel,  as, 
for  example,  the  pipes  and  chambers  of  a  pump,  and  so  that 
the  pump  is  completely  emptied  of  air,  then  the  outside  air 
will  exert  a  force  or  pressure  of  about  15  Ibs.  to  the  square 
inch  upon  all  of  the  outside  surface  of  the  pump  or  vessel  so 
emptied,  and  there  will  be  no  corresponding  or  balancing  pres- 
sure inside  of  the  pump  or  other  vessel.  Therefore,  it  follows, 
that  if  this  outer  air  is  pressing  down  upon  the  surface  of  the 
water  in  a  pump  well,  which  it  is  at  all  times,  if  the  air  is 
removed  from  the  inside  of  the  pump,  and  if  a  pipe  connects 
from  beneath  the  surface  of  the  water  in  the  well  to  the  interior 
of  the  pump,  then  the  water  in  the  well  will  be  forced  up  and 
through  the  pipe  and  into  the  pump  by  the  atmospheric  or 
natural  air  pressure  at  the  outside. 

This  action  is  perfectly  satisfactory  and  complete  so  far  as  it 
is  able  to  go.  But,  as  already  pointed  out,  the  weight,  force, 
or  pressure  of  the  natural  air  being  fixed  and  limited  within 
certain  narrow  bounds,  and  the  weight  of  water  being  also  fixed 
and  limited  in  its  weight  within  certain  narrow  bounds,  it 
follows  that  there  is  also  a  limit  to  the  height  to  which  the  air 
pressure  will  force  or  "  lift "  the  water  in  a  pipe  or  vessel.  And 
it  is  within  this  limit  of  height  or  lift  that  we  must  manage  to 
keep  when  attempting  to  successfully  design  or  operate  a  pump- 
ing engine.  This  action  of  the  natural  air  lifting  or  forcing 
water  up  a  pipe  or  tube  when  the  air  within  the  pump  or  other 
vessel  is  removed  or  partially  removed,  is  technically  called 


232  PUMPING  ENGINES 

and  is  generally  known  by  the  name  of  "suction."  And  the 
word  "suction"  is  good  enough,  perhaps,  for  the  purpose  of 
expressing  a  certain  action  or  performance,  but  in  the  sense 
of  its  meaning  that  the  water  is  drawn  up  the  pipe  and  into  the 
pump,  it  is  absolutely  in  error  and  out  of  place.  In  fact  there 
is  no  such  action  as  "suction"  so  far  as  it  is  made  to  mean  the 
"pulling  "  or  "drawing"  of  wrater  from  a  lower  to  a  higher  level 
by  a  force  situated  higher  up  or  at  a  higher  level.  The  water 
is  not  drawn  up  at  all  by  something  in  front  of  it.  It  is  driven 
up  or  forced  up  by  something  behind  it.  And  that  something 
behind  the  water  is  the  natural  atmosphere  or  air  we  breathe; 
and  speaking  of  breathing,  the  action  of  a  pump  is  of  precisely 
the  same  nature  as  breathing;^ the  muscles  of  the  chest  and 
pulmonary  regions  distend  or  enlarge  the  chambers  and  passage- 
ways in  the  lungs,  thus  causing  a  partial  vacuum,  and  thus 
enabling  the  outer  air  to  force  its  way  into  what  we  call  our 
breathing  spaces.  To  illustrate  this,  let  any  one  place  the 
tube  of  an  ordinary  vacuum  gauge  to  the  lips,  close  the  nose 
and  then  go  through  the  operation  of  breathing  or  drawing 
in  breath.  The  vacuum  gauge  will  at  once  indicate  to  what 
extent  such  muscular  efforts  are  effective.  A  vacuum  from  18 
to  21  inches  on  a  mercury  column,  or  a  Bourdon  tube  gauge, 
may  be  readily  formed  by  the  breathing  experiment.  The 
attempt  to  form  a  vacuum  in  a  pump  will  be  followed  by  pre- 
cisely the  same  result;  only  a  body  of  water  being  situated 
between  the  outer  air  and  the  inner  space,  instead  of  the  air 
getting  in  as  in  the  case  of  breathing  with  the  lungs,  the  outer 
air  drives  the  water  into  the  pump  ahead  of  itself,  the  result 
being  that  so  long  as  water  enough  comes  into  the  well  to  keep 
the  water  surface  above  the  bottom  of  the  pipe  leading  into 
the  pump,  commonly  called  the  suction  pipe,  no  air  can  get 
in  at  all,  but  a  constant  stream  or  flow  of  water  will  take  place 
up  the  pipe  and  into  the  pump.  The  term  "vacuum/'  as  many 
people  are  more  or  less  aware,  signifies  a  complete  emptiness 
and  absence  of  everything,  air,  vapor,  gas,  water,  and  all  else 
tha'i  we  know  of.  And  into  a  vacuous  space  any  and  all  gases, 


SUCTION  LIFT  AND  SUCTION  PIPES  233 

atmospheres,  or  any  expansive  fluid  will  endeavor  to  penetrate 
and  flow.  A  vacuum  has  no  substance  or  properties  of  its  own, 
beyond  the  property  of  complete  emptiness,  and  does  not  draw 
nor  suck  nor  do  any  kind  of  work.  It  is  simply  a  condition 
which  offers  a  chance  for  work  to  be  done. 

The  extreme  height  to  which  the  natural  air  pressure  will 
force  or  drive  up  a  column  of  water  into  a  vacuum,  is  about 
34  ft.,  which  simply  means  that  within  a  vessel  containing 
no  air  whatever  nor  anything  else,  but  connected  by  a  pipe  with 
a  well  containing  water,  a  column,  or  head,  or  height,  of  water 
of  about  34  ft.  will  just  balance  the  entire  pressure  or  weight 
of  the  natural  air  resting  upon  the  surface  of  the  water  in  the 
well.  The  water  will  go  no  higher  than  about  34  ft.  no  matter 
how  perfect  the  vacuum  may  be,  or  how  large  the  chamber  or 
vessel  may  be  abpve  the  34  ft.  level.  This  head  of  34  ft.  of 
water  represents  a  pressure  of  about  15  Ibs.  per  square  inch, 
or,  to  be  more  exact,  a  pressure  of  14.7  Ibs.  per  square  inch. 

Considering  the  fact  that  the  getting  of  the  water  up  the 
supply  pipe  and  into  the  pump  is  widely  recognized  by  the 
technical  name  of  "suction"  it  will  be  expedient  and  conven- 
ient to  preserve  the  expression  and  so  this  part  of  the  opera- 
tion of  a  pump  will  be  so  designated,  the  foregoing  explana- 
tion that  there  is  no  such  thing  as  a  pulling  action  in  the  suction 
process  having  been  made  simply  to  place  the  actual  facts  in 
the  case  clearly  before  the  mind  of  the  reader  and  student. 
The  practical  effect  then  of  suction  in  a  pump  is  to  utilize  a 
portion  of  the  34  ft.  head,  or  say  14.7  Ibs.  of  force  to  over- 
come the  difference  in  level  between  the  surface  of  the  well 
and  the  height  in  the  pump  to  which  the  water  must  be  "lifted" 
by  suction;  and  then  utilize  the  balance  or  remaining  portion 
of  this  force  for  maintaining  the  flow  of  the  water  into  the 
pump  by  overcoming  the  friction  and  other  resistances  in 
the  moving  water.  And  in  following  out  this  idea,  it  becomes 
at  once  plain  that  the  higher  the  water  must  be  lifted  into  the 
pump,  the  slower  must  be  the  rate  of  flow,  as  the  available 
force  of  14.7  Ibs.  is,  within  very  narrow  limits,  a  fixed  and 


234  PUMPING  ENGINES 

unalterable  one;  the  logic  of  this  being  that  with  no  lift  at  all 
to  the  water,  the  entire  force  of  the  atmosphere,  14.7  Ibs.,  would 
be  available  for  overcoming  the  friction  of  flow;  and  contrary 
to  this,  with  a  lift  equal  to  34  ft.  or  the  equivalent  of  the  entire 
atmospheric  force  of  14.7  Ibs.  there  would  be  nothing  at  all 
available  for  overcoming  the  friction  of  flow  through  the  suc- 
tion pipe  and  into  the  pump. 

Therefore,  when  there  is  a  choice  in  the  matter  as  to  how 
much  to  allow  for  lift  and  how  much  to  allow  for  flow,  judg- 
ment based  upon  experience  comes  into  the  case,  and  good 
practice,  when  free  to  choose,  chooses  from  12  to  15  ft.  for  the 
lift  when  the  well  is  fairly  close  to  the  pumps  and  is  supplied 
with  water  by  an  easy  flow  from  the  source  of  supply;  and 
the  balance  of  from  19  to  22  ft.  is  then  available  for  overcoming 
the  resistances  to  the  flow  through  the  suction  pipe  and  into 
the  plunger  chambers.  A  suction  lift  of  20  ft.  could  be  tol- 
erated and  sometimes  we  are  confronted  with  conditions  de- 
manding more  than  20  ft.  lift,  even  so  high  as  26  ft.,  but 
every  possible  effort  should  be  made  to  avoid  going  above  20 
ft.,  and  if  a  height  of  so  much  as  26  ft.  is  absolutely  unavoid- 
able under  any  certain  set  of  conditions,  then  of  course  it  must 
be  met,  but  it  will  be  with  a  feeling  that  the  best  and  most 
desirable  results  in  pumping  water  are  unattainable.  Where  it 
is  necessary  to  flow  the  water  through  an  artificial  conduit  for 
a  considerable  distance  and  into  a  limited  well  for  the  engine  to 
take  its  supply  from,  a  suction  lift  of  26  ft.  would  be  absolutely 
perilous  to  the  machinery,  and  in  such  a  case  the  level  of  the 
water  in  the  well  should  be  kept  as  near  to  the  elevation  of  the 
discharge  valve  decks  as  possible,  say  within  4  or  5  ft. 

Even  the  actual  difference  between  the  surface  of  the  water 
in  the  well  and  the  extreme  height  of  necessary  suction  limited 
to  20  ft.,  there  will  then  be  a  loss  in  getting  the  water  through 
the  suction  valves  of  the  pump  before  the  net  amount  of  pres- 
sure available  for  flow  becomes  apparent.  The  resistance  of 
the  water  passing  through  a  set  of  suction  valves  properly 
proportioned  to  a  pump,  is  taken  as  the  results  of  experiment 


SUCTION  LIFT  AND  SUCTION  PIPES  235 

and  observation  at  one  foot  head;  so  that  we  have  the  sum- 
mary of  the  suction  or  inlet  account  as  follows  for  good  eco- 
nomical limits  with  a  liberal  well  close  at  hand,  and  a  free  flow 
from  the  source  of  supply: 

Actual  net  lift  accomplished  between  the  level  of  the 
water  in  the  well  and  the  under  side  of  the  dis- 
charge valves  in  the  main  pumps  in  the  engine  .  .  20  feet. 

Resistance  of  the  suction  valves 1  foot. 

Available  for  friction  of  flow      ' 13  feet. 

Total  atmospheric  force  at  sea  level 34  feet. 

The  unemployed  head  of  13  ft.,  aside  from  the  height  of  the 
water  column  and  the  resistance  of  the  suction  valves  and 
seats,  is  not  all  available  for  overcoming  friction  in  a  straight 
pipe  and  so  it  is  not  safe  to  work  completely  up  to  the  limit 
as  might  at  first  appear;  as  a  break  or  loss  of  the  suction  col- 
umn is  extremely  liable  to  produce  serious  damage  to  the 
engine  by  placing  it  in  the  position  of  exerting  power  enough 
at  the  steam  end  to  do  a  certain  amount  of  work  and  then 
being  suddenly  robbed  of  most  of  its  resistance.  Therefore 
it  is  best  to  allow,  say,  5  ft.  for  a  margin  of  safety,  and  so  reduce 
the  13  ft.  to  8  ft.  This  is  again  liable  to  reduction  on  account 
of  the  entering  head  necessary  at  the  intake  end  of  the  suction 
pipe,  and  also  on  account  of  the  bends  in  the  suction  pipe  on 
its  way  from  the  well  to  the  pump,  and  it  is  scarcely  possible 
to  get  along  with  less  than  four  changes  in  direction  in  the 
course  of  the  inflowing  water ;  one  bend  at  leaving  the  well 
at  the  top  of  the  vertical  column;  one  in  turning  towards  the 
pump  near  or  within  the  building;  one  turning  into  the  pump 
chamber ;  and  one  more  in  turning  directly  towards  the  suc- 
tion valves.  Of  course  some  conditions  and  situations  might 
reduce  the  number  of  changes  in  motion  and  direction  to  three, 
but  not  frequently,  and  in  generalizing  results  it  is  always 
better  to  take  an  extreme  view  on  the  adverse  side  of  the  ques- 
tion when  dealing  with  such  an  absolutely  fixed  factor  as  "  suc- 
tion lift,"  it  being  remembered  that  the  hydraulic  engineer 


236  PUMPING  ENGINES 

aims  mostly  to  arrive  at  a  safe  conclusion  so  as  to  insure  the 
results  sought  for,  rather  than  to  ascertain  the  exact  balance 
of  all  of  the  factors  involved.  This  latter  accomplishment 
is  absolutely  impossible  on  account  of  the  unknown  changes 
in  conditions  and  the  inevitable  errors  in  human  judgment  and 
workmanship,  always  present  in  practical  operation. 

The  loss  in  head  sustained  by  flowing  water  through  a  pipe 
is  not  great  with  properly  designed  bends,  but  is,  nevertheless, 
something  to  be  allowed  for  when  dealing  with  such  a  small 
amount  of  fixed  pressure;  it  depends  upon  the  length  or  the 
shortness  of  the  bend,  although  not  in  direct  proportion,  the  resis- 
tance increasing  rapidly  in  very  short  bends  after  the  radius 
of  the  bend  becomes  less  than  one  diameter  of  the  pipe, 
culminating  at  a  radius  of  bend  equal  to  half  a  diameter  of  the 
pipe,  which  is  the  least  radius  possible  to  make  in  a  pipe  bend, 
as  then  the  inner  "corner"  of  the  bend,  so  to  speak,  will  be  a 
perfect  right  angle  in  a  90  degree  bend.  After  the  radius  of  the 
bend  reaches  five  times  the  diameter  of  the  pipe  the  effect 
seems  to  be  the  same  as  though  a  straight  pipe  were  used,  but 
practically  it  will  be  good  practice  to  allow  one  quarter  or  0.25 
of  a  foot  head  for  each  bend  in  discounting  the  atmospheric 
force  for  driving  water  into  a  pumping  engine,  as  then  it  will 
be  known  that  the  flow  of  water  will  be  without  interruption 
from  this  item;  with  four  bends  this  allowance  will  further 
reduce  the  net  force  for  causing  flow  down  to  7  ft.  With  the 
form  of  bottom  to  the  suction  pipe  used  by  the  writer  there 
need  be  no  allowance  for  entering  head  at  the  point  where  the 
water  enters  the  pipe  down  in  the  well;  this  form  being  a  bell 
mouth,  with  an  outer  diameter  twice  the  internal  diameter 
of  the  body  of  the  pipe.  If  a  foot  valve  is  used,  but  which  is 
unnecessary  excepting  at  rare  intervals  and  under  some  sort 
of  abnormal  conditions,  of  course  there  will  be  a  resistance  to 
be  added  for  this  item  amounting  perhaps  to  one  foot,  so  that 
with  a  foot  valve  the  net  available  force  for  sending  the  water 
to  the  pump  on  the  basis  of  the  length  of  a  straight  pipe  equal 
to  the  total  length  of  suction  pipe,  including  length  of  bends, 


SUCTION  LIFT  AND  SUCTION   PIPES  237 

would  be  6  ft.  under  ordinary  good  conditions,  with  a  total 
measured  suction  lift  of  20  ft.,  and  with  all  losses  of  head 
accounted  for  and  deducted. 

Regarding  the  resistance  of  water  flowing  around  bends  in 
pipes,  there  are  well  received  conclusions  based  upon  a  formula 
from  high  authorities  on  the  subject  of  hydraulics,  but  there 
is  an  amount  of  complex  mathematics  involved  which  would 
be  out  of  place  in  a  book  of  this  character  and  aims,  and,  there- 
fore, the  writer  in  considering  the  mathematics  of  the  matter, 
together  with  the  factors  of  roughness  and  irregularity  actually 
found  in  the  work  of  making  suction  pipes  for  pumping  engines, 
gives  as  a  safe  practical  conclusion  the  allowance  of  0.25  of  a 
foot  for  each  change  in  direction  of  the  water  in  its  progress 
from  the  pump  well  to  the  plunger  barrel  of  the  main  pump. 

Regarding  the  use  of  a  foot  valve,  there  is  really  no  reason 
for  such  an  appliance  in  a  great  majority  of  cases,  as  the  writer 
has  very  fully  demonstrated  during  the  past  three  or  four 
years  in  the  installation  of  the  largest  and  highest  types  of 
modern  crank  and  fly  wheel  pumping  engines.  Even  with  the 
Worthington  high  duty  engine,  a  machine  which  has  always 
been  supposed  to  greatly  need  a  foot  valve  so  as  to  insure  the 
complete  filling  of  the  pipes  and  chambers  with  solid  water 
before  starting,  there  is  at  least  one  case  wherein  the  foot  valve 
was  removed  from  the  bottom  of  the  suction  pipe  of  a  6,000,000 
gallon  engine  of  this  type,  and  under  a  14-foot  suction  lift  no 
inconvenience  whatever  followed.  So  that  what  was  tried  as 
an  experiment  was  continued  as  a  fixture  for  several  years  and 
continues  so  at  present. 

With  6  ft.  as  found  above  for  a  head  to  overcome  the  friction 
in  the  flowing  water,  well  known  formulae  will  give  a  much 
higher  velocity  than  is  generally  reckoned  for  water  going  into 
pumps  and  suction  pipes,  but  the  flowing  of  water  into  a  pump 
is  not  continuous  and  uninterrupted  as  in  the  case  of  simply 
sending  the  water  to  a  given  point  by  a  continuous  flow.  At 
the  instant  of  the  closing  of  the  suction  valves  at  the  end  of 
the  stroke  of  the  plunger,  the  water  is  completely  stopped  at 


238 


PUMPING   ENGINES 


that  end  of  the  pump  and  must  be  promptly  not  to  say  suddenly 
started  into  the  opposite  end  of  the  plunger  chamber  or  into 
another  plunger  chamber  which  has  just  been  discharged  of 
its  water.  So  that  the  velocity  expressed  in  feet  per  second 
from  a  formula  is  largely  discounted  by  the  manner  in  which  a 
pump  actually  takes  its  water,  and  the  diameter  of  the  suction 
pipe  is  brought  up  in  practice  to  what  has  been  observed  as  a 
fair  practical  figure,  obtained  by  comparing  the  theoretical 
discharge  with  the  ordinary  actual  rates  of  flow. 

The  final  results  of  these  determinations  produce  the  follow- 
ing table  of  suction  pipes  for  pumping  engines  of  various  capa- 
cities, based  upon  ordinary  lengths  of  such  pipes  practicable 
to  be  used  in  regular  work.  If  it  seems  to  be  necessary  to  use 
much  longer  suction  pipes  than  are  ordinarily 'found,  say,  con- 
siderably longer  than  50  ft.  for  large  pipes,  it  will  be  found  the 
better  practice  to  flow  the  water  by  gravity  to  a  suction  well 
nearer  to  the  engine  even  at  the  cost  of  considerable  trouble 
and  expense.  Of  course  longer  suction  pipes  can  be  used  when 
we  are  driven  to  it  by  the  necessities  of  a  situation,  but  the 
best  results  will  not  be  obtained  from  the  plant  with  extremely 
long  suction  pipes,  even  though  enlarged  diameters  are  employed 
to  keep  down  the  friction  flow. 

Table  of  suction  pipes  not  over  50  feet,  long  and  with  not  more  than 
four  changes  of  direction  in  the  flow  of  the  water  from  the  well  to 
the  suction  valves. 


13.  S.  GALLONS 

PER 

24  HOURS. 

INTERNAL 
DIAMETER  FOR 
20  FEET  LIFT. 
Inches. 

1,000,000 

10 

2,000,000 

12 

3,000,000 

16 

5,000,000 

20 

8,000,000 

24 

10,000,000 

30 

12,000,000 

36 

15,000,000 

40 

20,000,000 

48 

25,000,000 

54 

30,000,000 

60 

35,000,000 

66 

40,000,000 

72 

SUCTION  LIFT  AND  SUCTION  PIPES  239 

These  sizes  would  answer  for  something  more  than  20  ft. 
suction  lift,  and  would  do  no  harm  for  less  than  20  ft.,  so,  per- 
haps, the  table  would  answer  as  a  standard  table  for  regular 
work.  The  difference  in  cost  would  be  trifling  between  these 
sizes  and  the  least  that  could  be  gotten  along  with  at  all,  and 
one  case  of  trouble  from  too  small  a  suction  pipe  would  wipe 
out  any  saving  possible  in  several  cases,  by  reducing  the  diam- 
eter materially.  And  aside  from  this,  the  economy  involved 
in  the  use  of  standard  sizes  in  manufacturing  is  obvious. 

The  proper  and  complete  bolting  of  suction  pipe  joints  need 
hardly  to  be  dwelt  upon  it  would  seem,  but  a  brief  mention 
of  its  importance  will  be  in  good  place  here,  if  for  nothing  more 
than  to  emphasize  the  great  value  of  absolutely  air  tight  joints 
where  such  a  delicate  effect  as  the  maintaining  of  a  perfect 
vacuum  is  concerned.  Whenever  it  becomes  evident  that  an 
air  leakage  does  exist  in  some  part  of  the  suction  connections, 
it  is  an  almost  endless  task  to  discover  and  locate  the  trouble; 
it  generally  being  found  necessary  to  thoroughly  paint  the 
entire  pipe  with  all  of  its  joints,  so  as  to  cover  the  inlet  of  air 
wherever  it  may  be,  the  difficulty  of  locating  small  but  trouble- 
some leaks  being  all  but  insurmountable.  It  is  assumed  by 
some  that  because  the  effects  of  pressure  involved  in  the  uses 
of  a  vacuum  are  very  slight,  the  bolting  of  the  suction  joints 
need  be  only  nominal,  and  not  to  be  very  seriously  considered 
as  compared  with  joints  for  pipes  under  pressure  of  the  discharge 
portions  of  the  pump;  but  in  such  a  position  there  are  many 
chances  for  annoying  and  expensive  mistakes,  and  therefore 
the  writer  makes  no  distinction  between  the  bolting  of  the 
suction  and  the  discharge  pipes  so  far  as  concerns  number  and 
size  of  bolts,  the  idea  being  that  the  loss  of  vacuum,  although  a 
rather  delicate  matter  to  deal  with,  is  of  too  much  importance 
to  the  well  being  and  proper  operation  of  the  pumps  to  permit 
anything  but  the  greatest  means  of  assurance  of  complete 
and  perfect  workmanship. 

Therefore  the  following  table  is  presented  as  a  guide  in  the 
laying  out  of  suction  pipe  joints,  and  which,  although  costing 


240 


PUMPING  ENGINES 


a  little  more  than  joints  made  with  fewer  and  smaller  bolts, 
will  nevertheless  pay  to  use  where  absolute  assurance  of  air 
tight  joints  is  desired,  especially  when  it  is  considered  that 
settlement  strains,  contractions,  and  expansions,  and  other 
possible  distortions  n  the  suction  pipe,  all  tend  to  cause  a 
letting  up  at  the  joints  where  the  bolting  is  not  solid  and  se- 
cure. This  table  is  laid  out  upon  a  standard  line  for  pipe 
joints,  for  pipes  under  heavy  internal  pressures  such  as  force 
mains  and  the  like,  and  will  be  found  to  give  very  satisfactory 
results  in  holding  the  packing  in  place  between  the  flanges  so 
as  to  prevent  air  leakages. 


Table   showing  inside   diameter  of  suction  pipes;  sizes   of  flanges; 
number  and  sizes  of  bolts ;  and  diameter  of  bolt  circles. 


DIAMETER 
OF  SUCTION 
PIPE,  INSIDE, 
INCHES. 

OUTSIDE 
DIAMETER 
OF  FLANGES, 
INCHES. 

FINISHED 
THICKNESS 
OF  FLANGES, 
INCHES. 

DIAMETER 

OF 

BOLT  CIRCLE, 
INCHES. 

NUMBER 

OF 

BOLTS. 

DIAMETER 

OF 

BOLTS, 
INCHES. 

10 

16 

1 

14J 

12 

3 
f 

12 

19 

iA 

16£ 

12 

16 

23  $ 

!i 

2H 

16 

| 

20 
24 

27* 
32 

If 

25 

29i 

20 

24 

1 
1 

30 

38| 

l] 

36 

28 

1* 

36 
40 

45f 

50 

1! 

42f 
46| 

32 
36 

1! 

48 

59} 

2 

56 

44 

if 

54 

66 

21 

61J 

50 

If 

60 

74 

21 

68J 

56 

if 

66 

80 

2f 

74  1 

60 

H 

72 

88 

2f 

821 

66 

2 

CHAPTER   XVIII 
WATER  PASSAGES  AND  PUMP  VALVES 

WHERE  the  suction  pipe  delivers  the  water  to  the  suction 
chamber  of  the  main  pump,  beneath  the  suction  valves, 
the  passages  and  openings  should  be  ample  and  of  favorable 
form  to  permit  of  the  flow  with  the  least  disturbance  and 
breaking  up  into  small  divisions  until  the  water  is  actually 
delivered  to  the  suction  valve  gratings  or  seats,  where  it 
separates  into  small  streams  for  transmission  through  the 
seats  beneath  the  valves,  and  into  the  plunger  chamber  of  the 
pump. 

Upon  the  return  stroke  of  the  plunger,  the  suction  valves 
are  closed,  the  water  pressure  is  suddenly  raised  up  to  that 
in  the  force  chamber  or  the  space  above  the  discharge  valves, 
and  so  the  water  is  forced  out  of  the  plunger  chamber  and  out 
of  the  pump  into  the  delivery  pipe  or  force  main. 

The  operation  of  pumping  water  is  simple  and  well  known 
and  has  been  long  known  in  general  terms,  but  it  is  surprising 
how  many  bad  and  rough  working  pumps  have  been  produced 
in  this  world.  Many  troubles  have  been  met  with  by  ignoring 
a  few  simple  and  necessary  principles,  among  them  being  a 
desirability,  not  to  say  necessity,  for  direct  lines  for  the  pas- 
sage of  the  water  through  the  pump; -the  avoidance  of  reverse 
currents  and  places  for  lodgment  of  the  air  present  more 
or  less  in  all  free  out  door  water;  design  and  construction  re- 
quired to  easily  and  safely  meet  the  sudden  reversal  from  suc- 
tion to  discharge;  keeping  the  water  so  far  as  possible  moving 
in  an  upward  direction  continuously  and  uniformly;  design 
and  construction  so  that  the  working  forces  and  pressures  are 
properly  met  by  corresponding  support  in  the  structure  of 

241 


242  PUMPING  ENGINES 

the  pump  body,  or  by  transmission,  safely  and  directly  to 
the  foundations  or  framing,  etc. 

The  pump  valves  come  in  for  a  very  careful  consideration, 
and  have  been  the  cause  of  much  debate  and  contention. 
Beginning  in  the  far  distant  past,  with  one  or  a  very  few  large 
valves,  pump  valves  have  nowadays  been  brought  to  the 
common  practice  by  nearly  all  makers  and  in  nearly  all  designs 
of  pumps,  of  a  nest  or  group  of  comparatively  small  valves, 
for  the  most  part  consisting  of  rubber  discs  varying  in  diam- 
eter, in  thickness,  and  in  hardness,  but  little  for  equal  con- 
ditions or  service.  And  by  adopting  these  small  valves  great 
convenience  and  economy  in  manufacture  of  pumping  engines 
are  secured,  principally  because  with  a  desirable  size  of  valves, 
say  from  3  to  5  inches  in  diameter,  a  greater  or  less  number 
may  be  made  to  suit  the  demands  for  smaller  or  larger  pumps, 
and  at  the  same  time  permit  the  manufacture  of  valves  and 
seats  in  large  quantities,  with  the  assurance  that  they  can  be 
used  to  advantage  and  economy.  Previously  to  the  advent  of 
the  Worthington  pumping  engine,  about  50  years  ago,  the  prac- 
tice of  very  large  single  valves  prevailed  in  water  works  pumps 
of  considerable  size  and  capacity,  but  Henry  R.  Worthington, 
then  engaged  in  producing  an  engine  to  retain  whatever  advan- 
tages he  could  see  in  the  Cornish  engine  then  in  its  glory,  and 
to  omit  the  disadvantages  clearly  apparent,  conceived  the  idea 
of  replacing  the  single  large  valve  with  a  number  of  small  ones, 
an  advantage  in  construction  and  operation  quickly  to  be 
recognized  and  adopted  by  pump  makers  ever  since. 

Fig.  66  is  an  illustration  of  a  typical  pump  valve  for  water 
works  engines,  and  although  this  specific  size  and  design  is 
sometimes  departed  from,  nevertheless  the  illustration  indi- 
cates a  valve  which  can  be  used  in  a  very  large  number  of  pumps; 
and  this  being  the  case  the  great  economy  of  its  manufacture 
in  special  machines  becomes  apparent  at  once. 

The  valve  seats  are  sometimes  screwed  into  the  valve  decks, 
sometimes  pressed  in  without  the  use  of  screw  threads,  some- 
times bolted  into  place;  but  the  manner  of  attachm?nt  most 


WATER  PASSAGES  AND  PUMP   VALVES 


243 


favored,  and  no  doubt  justly  so,  for  water  works  engine 
pumps,  is  the  screwing  in  by  a  tapering  thread  of  a  brass 
valve  seat  into  the  cast  iron  valve  deck  formed  within  the 
pump  body;  the  brass  seat 
being  sent  firmly  home  into 
its  socket  by  means  of  some 
sort  of  a  power  driven  ma- 
chine or  tool. 

The  valve  stems,  which  pass 
through  the  center  of  the 
valves,  generally  a  separate 
piece  from  the  seat,  and  in 
turn  generally  screwed  into 
the  center  of  the  seat,  is 
formed  at  its  upper  or  outer 
end  into  a  shoulder  or  guard 
to  hold  the  spring  in  place 
and  afford  a  hold  for  the 
wrench  in  putting  in  and  tak- 
ing out  the  stem  when  the 
valve  itself  is  replaced. 

Of  course  there  have  been 
a  number  of  different  kinds 
of  pump  valves  used  in  the 
past,  and  some  different  ones 
are  still  used,  but  the  gen- 
eral practice  is  pretty  well 
settled  down  very  nearly  to 
the  valve  and  seat  shown  in 
the  illustration.  For  example, 
Fig.  67  is  an  illustration  of  another  form  of  pump  valve  used 
a  good  deal  at  the  present  time.  Its  general  features  are  the 
same  as  Fig.  66,  as  in  this  one  also  the  seat,  the  central  stem, 
the  guard  and  spring,  are  of  brass;  but  the  stem  and  guard  are 
separate,  the  stem  being  screwed  into  and  then  riveted  at  the 
under  side  of  the  seat;  the  guard  holding  the  spring  down 


Fig.  66.  —  Typical  Pump  Valve  for 
Water  Works  Engines. 


244 


PUMPING  ENGINES 


onto  the  brass  valve  plate  is  screwed  onto  the  upper  end  of 
the  stem  and  then  a  split  pin  or  cotter  is  put  through  the 
stem  above  the  guard  to  avoid  all  chances  of  the  guard  back- 
ing off;  the  edge  of  the  plate  on  top  of  the  valve  is  turned 
down  around  the  upper  outer  edge  of  the  rubber  valve  for 
support  of  the  valve  under  pressure.  In  Fig.  67  the  area  is 
4f  square  inches  through  the  valve  seat,  and  the  diameter  of 
the  inner  edge  of  the  valve  seat  ring  is  3  inches,  making  it 


Fig.  67.  —  Typical  Pump  Valve  for  Water  Works  Engines. 

« 

necessary  for  the  valve  to  lift  one  half  an  inch  to  give  a  rim 
area  equal  to  the  area  through  the  seat;  but  the  velocity  of  the 
water  is  no  doubt  greater  at  the  rim  than  in  the  seat  opening 
and  so  as  a  matter  of  fact  in  all  probability  a  valve  never  needs 
to  lift  enough  to  make  the  rim  area  equal  to  the  seat  area. 

The  matter  of  total  valve  area,  or  total  area  of  valve  seat 
opening,  has  also  been  much  talked  about  and  disputed  over 
but  such  area  ought  to  depend  upon  the  velocity  needed  to 


WATER  PASSAGES  AND  PUMP  VALVES  245 


pass  the  required  quantity  of  water  in  a  given  time.  Some 
authorities  advocate  a  velocity  not  to  exceed  3  ft.  per  second, 
and  some  set  the  limit  at  4  ft.  per  second;  but  there  are  several 
factors  to  be  considered.  First  as  to  the  lift  of  the  valves;  the 
lower  the  pressure  and  the  lower  the  rate  of  revolution  of  the 
engine,  the  higher  the  valve  can  lift;  and  to  the  contrary,  the 
higher  the  pressure  and  the  higher  the  rate  of  revolution  of 
the  engine,  the  less  the  valve  may  lift,  if  a  smooth  running  engine 
is  desired. 

Assuming  the  valves  to  be  not  more  than  4  inches  nor  less 
than  3^  inches  in  diameter,  the  following  table  of  extreme  lift 
of  valves  and  revolutions  of  the  engine  will  give  good  results: 


WATER  PRESSURE, 
POUNDS. 

LIFT  OF  PUMP 
VALVES, 
FRACTION  OF 
AN  INCH. 

SPEED  OP 

ENGINE, 
REVOLUTIONS 
PER  MINUTE. 

50 

, 

20 

50 

I 

30 

50 

| 

40 

60 

| 

30 

60 

1 

35 

70 

I 

25 

70 

30 

80 

1 

25 

80 

i 

30 

90                           | 

25 

90 

i 

30 

100 

3 

S 

23 

100 

I 

25 

120 

I 

8 

20 

120 

* 

23 

130 
140 

20 

18 

150 

1 
4 

17 

As  is  well  known,  many  attempts  have  been  made  to  have 
fast  running  pumping  engines  with  high  lift  of  pump  valves, 
and  in  some  cases  fairly  good  results  have  been  obtained,  but 
seldom  if  ever  do  such  engines  operate  without  a  great  deal  of 
noise  and  wear  of  pump  valves;  but  contrary  to  this,  when  we 
see  a  quiet,  smooth  running  pumping  engine  under  fairly  good 
water  pressure,  it  will  always  be  found  that  a  very  liberal  area 


246 


PUMPING  ENGINES 


of  pump  valves  has  been  provided  and  consequently  having 
small  lift  to  pass  the  desired  quantity  of  water. 

As  to  the  area  through  the  valve  seats  or  gratings,  upon  which 
the  regular  form  of  rubber  pump  valves  rest,  3  ft.  per  second 
as  the  velocity  of  the  water  through  the  seats,  for  a  general 
rule  and  in  the  absence  of  any  special  conditions,  will  be  found 
to  be  very  satisfactory  and  give  a  good,  smooth  running  pump. 
A  rate  of  4  ft.  per  second  will  answer  in  many  cases,  and  will 
at  most  times  be  acceptable  where  the  pressure  and  the  lift 
of  the  valves  are  not  too  high;  but  3  ft.  per  second  is  to  be  pre- 
ferred as  the  speed  for  smooth  action  and  long  life  of  the 
machine  with  low  rate  of  repairs.  The  following  table  gives 
the  net  area  through  the  valve  seats  for  different  kinds  of 
pumping  engines  calculated  at  3  ft.  per  second  for  the  velocity 
of  the  water  going  through : 

Area    through  suction   valve   seats  for   various   capacities.     Two    double 

acting  plungers. 


WATER  THROUGH 

•  EACH  PLUNGER. 

VALVE  SEATS, 
MOVING  3  FEET 

REVOLU- 

TIONS 
PER 

MINUTE. 

TRAVEL, 
FKET  PER 
MINUTE. 

U.  S.  GALLONS 

PER 

24  HOURS. 

PER  SECOND. 
AREA  OF  SUCTION 
VALVE  SEAT 
OPENINGS  IN 
SQUARE  INCHES, 
FOR  EACH  END  OF 

Diameter. 
Inches. 

Stroke. 
Inches. 

EACH  PLUNGER. 

9 

18 

45 

135 

1,280,000 

48 

12 

24 

36 

144 

2,400,000 

90 

15 

30 

31 

155 

4,000,000 

153 

18 

36 

27 

162 

6,000,000 

228 

21 

42 

24 

168 

8,600,000 

323 

24 

48 

22 

176 

11,800,000 

443 

27 

54 

21 

189 

16,000,000 

601 

30 

60 

20 

200 

20,000,000 

784 

33 

66 

19 

209 

26,500,000 

998 

36 

72 

18 

216 

32,600,000 

1,220 

For  two  single  acting  plungers  the  figures  will  be  the  same 
so  far  as  diameter  of  plungers,  revolutions  per  minute,  and 
area  of  valve  seat  openings,  are  concerned,  but  the  capacities 
per  24  hours  will  be  only  one  half  those  given  in  the  table,  so 


WATER  PASSAGES  AND  PUMP  VALVES  247 

that  double  the  required  gallons  per  24  hours  will  show  in  the 
table  the  dimensions  for  single  acting  plungers. 

For  three  single  acting  plungers  the  figures  will  be  the  same 
so  far  as  diameter  of  plunger,  revolutions  per  minute,  and  area 
of  valve  seat  openings  are  concerned,  but  the  capacities  per 
24  hours  will  be  only  three  quarters  of  those  given  in  the  table, 
so  that  one  third  added  to  the  required  gallons  per  24  hours 
will  show  in  the  table  the  dimensions  for  three  single  act- 
ing plungers. 

For  example,  if  the  plungers  and  suction  valve  area  for 
8,000,000  gallons  per  24  hours  is  desired,  and  two  single  acting 
plungers  are  to  be  used,  the  8,000,000  must  be  doubled,  and 
then  the  diameter  of  plungers,  revolutions  per  minute,  feet 
travel,  and  valve  seat  openings  found  opposite  16,000,000 
gallons.  Or,  if  three  single  acting  plungers  are  to  be  used, 
the  8,000,000  gallons  is  to  be  increasd  one  third  or  to  the 
11,800,000  as  the  nearest  found  in  the  table,  and  the  dimensions 
opposite  the  latter  figure  will  be  correct  for  a  three  plunger 
engine  for  8,000,000  gallons  per  24  hours  under  the  conditions 
given  in  the  table. 

With  two  double  acting  plungers  in  crank  and  fly  wheel 
engines,  the  cranks  should  be  set  90  degrees  apart. 

With  two  single  acting  plungers  the  cranks  should  be  set 
180  degrees  apart. 

With  three  single  acting  plungers  the  cranks  should  be  set 
120  degrees  apart. 

With  the  non-rotative  or  Worthington  type  of  machinery, 
four  complete  strokes  would  be  taken  as  one  "revolution," 
although  as  a  matter  of  fact  there  are  no  revolutions  of  any- 
thing, there  being  no  wheel  in  its  make  up,  but  four  strokes 
would  rather  be  considered  as  one  "cycle"  corresponding  to 
one  revolution  of  the  wheel  engine.  So  that  one  "cycle" 
or  four  strokes,  two  double  strokes  at  each  side  of  the  machine, 
is  the  equivalent  of  one  revolution;  it  being  noted  in  passing 
that  there  must  be  four  operations  in  the  non-rotative  engine 
for  each  revolution,  and  two  single  acting  or  three  single  acting 


248  PUMPING  ENGINES 

plungers  cannot  be  employed  in  this  type,  although  four  single 
acting  plungers  can  be  and  are  sometimes  used.  Therefore 
the  non-rotative  engine  must  be  considered  as  a  "four  cor- 
nered" machine,  or  a  machine  with  two  double  acting  plun- 
gers and  in  no  other  class.  From  this  it  will  be  observed  that 
the  table  as  it  stands  accommodates  the  non-rotative  engine, 
with  the  possible  exception  that  this  type  is  not  often  oper- 
ated at  quite  so  high  a  speed  as  that  given  in  the  table,  but 
there  is  no  perceptible  reason  why  it  could  not  be  worked  at 
the  rates  given  with  the  proportions  of  diameter  of  plunger 
to  stroke,  and  with  the  valve  areas  given.  There  is  no  hard 
and  fast  rule  for  plunger  diameters,  length  of  stroke,  rates  of 
revolution,  and  other  details  to  be  implied  as  absolutely  neces- 
sary by  this  table,  but  the  writer  believes  after  many  years 
experience,  observation,  and  practice,  that  the  dimensions  and 
speeds  given,  will  produce  pumping  machinery  not  to  be  ex- 
celled and  probably  not  equaled  as  a  paying  investment  where 
usefulness  in  proportion  to  the  capital  involved  is  concerned. 
All  sorts  of  changes  have  been  tried  by  various  makers,  but 
the  record  is  held  to-day,  has  always  been  held,  and  likely 
always  will  be  held,  for  economy  and  long  life,  by  propor- 
tionately large,  slow  running  pumping  engines.  Repairs  and 
stoppages  are  the  most  expensive  items  encountered  in  pump- 
ing water,  and  these  should  be  reduced  to  a  minimum  by  put- 
ting money  enough  into  the  machinery  to  enable  it  to  handle 
its  work  with  smoothness  and  ease.  The  Worthington  old 
time,  long  stroke  pumping  engines  have  never  been  equaled 
for  low  repair  accounts  and  absolute  reliability  for  pumping 
water;  they  were  run  from  92  to  110  feet  per  minute  and  were 
generally  built  with  a  stroke  of  4  ft.  for  5,000,000  gallons  capa- 
city and  upwards.  The  high  duty  engines  of  to-day  of  all  types, 
which  give  the  greatest  economy,  are  long  stroke,  heavily  pro- 
portioned machines.  The  only  excuse  for  light  weight,  short 
stroke  pumping  engines  is  low  first  cost,  the  use  of  which  involves 
a  policy  too  often  leading  to  disappointment  and  loss  grossly  out 
of  proportion  to  the  deceptive  saving  in  capital  at  the  beginning. 


WATER  PASSAGES  AND  PUMP  VALVES  249 

Having  determined  the  proper  area  of  seat  openings  for  the 
suction  valves  of  a  pumping  engine  in  proportion  to  the  quan- 
tity of  water,  speed,  etc.,  which  will  give  the  best  all  around 
results,  least  resistance  and  loss  of  quantity  and  power  in  pass- 
ing the  water  through  the  suction  valves  into  the  pump,  or 
more  strictly  speaking,  into  the  plunger  chamber,  it  will  of 
course  be  certain  that  a  similar  application  of  areas  to  the 
discharge  valves  will  give  a  like  minimum  of  resistance  and 
loss  in  getting  the  water  out  of  the  plunger  chamber;  so  that 
the  application  of  the  same  tables  of  valve  details  given  for 
the  suction  valves  will  complete  the  pump  so  far  as  the  inlet 
and  outlet  of  water  are  concerned  through  the  valves  and  valve 
seats. 

As  already  pointed  out,  the  passageways  for  the  water  within 
the  pump  body,  from  the  suction  pipe  connection  to  the  suction 
valves,  within  the  plunger  chamber,  and  beyond  the  discharge 
valves  to  the  point  of  connection  of  the  force  main  to  the  pump 
body,  should  be  of  1  beral  dimensions  and  of  simple  forms,  so  that 
the  water  may  flow  in  as  direct  lines  as  possible  and  with  the 
least  resistance.  It  has  been  considered  by  the  best  and  most 
experienced  authorities  to  be  a  fair  allowance  to  add  one  foot 
for  loss  of  head  for  the  suction  valves,  and  one  foot  for  the 
discharge  valves,  to  the  observed  head  noted  by  gauge  and 
measurements,  this  allowance  of  two  feet  for  the  pump  end 
of  the  machine  to  represent  the  resistance  which  is  overcome 
by  the  power  end  of  the  machine  in  getting  the  water  into 
and  out  of  the  plunger  chamber,  and  which  cannot  be  made 
to  appear  although  the  work  is  really  done.  The  steam  engine 
indicator,  sometimes  used  for  indicating  the  operations  going 
on  inside  of  a  pump  barrel,  has  a  rather  hard  time  at  best, 
in  handling  such  a  stubborn  element  as  water,  and  is  wholly 
inadequate  to  demonstrate  with  sufficient  exactness  the  actual 
state  of  the  facts,  beyond  showing  by  a  diagram  the  general 
conditions  as  regards  either  the  presence  or  absence  of  abnor- 
mal and  violent  fluctuations  arising  from  shocks  in  the  water 
due  to  the  sudden  changes  of  form  or  speed  of  flow. 


CHAPTER   XIX 
THE  WATER  PLUNGERS 

IN  the  natural  course  of  things,  the  plunger  is  the  next  detail 
of  the  pump  to  be  taken  up  and  dealt  with.  There  is  not 
so  very  much  to  be  said  about  the  plunger;  it  is  a  cylindrical 
body  sliding  back  and  forth  or  up  and  down,  either  alternately 
into  and  partly  out  of  the  adjoining  valve  chambers  as  in  a 
double  acting  pump,  or  into  and  partly  out  of  a  single  plunger 
barrel  or  valve  chamber  as  in  a  single  acting  pump. 

The  end  or  ends  of  the  plunger  moving  within  the  body  of 
the  pump  are  shaped  according  to  the  ideas  or  fancies  of  the 
designer.  Round  nose,  pointed  nose,  concavo-convex  nose, 
and  other  forms  of  nose  or  end,  are  made  for  the  extremity  of 
the  plunger  which  comes  into  direct  contact  with  the  water 
within  the  pump.  The  various  shapes  simply  indicate  the 
various  ideas  of  designers  in  forming  a  plunger  end  which  will 
offer  the  least  resistance  to  the  moving  water,  and  move  with 
the  greatest  smoothness  and  freedom  from  shocks,  etc.  It  is 
not  so  far  evident  that  any  particular  form  of  end  has  affected 
the  efficiency  of  a  pumping  engine,  and  probably  a  half  ball 
or  half  sphere  is  as  good  as  any  form  for  the  end  of  a  water 
plunger. 

The  office  of  the  plunger  is  to  attempt  to  form  a  vacuum  by 
partly  withdrawing  from  the  valve  or  plunger  chamber  during 
the  suction  stroke  of  the  pump,  and  then  upon  the  return  or 
discharge  stroke,  to  form  a  pressure  within  the  plunger  chamber 
and  the  valve  chamber  above  the  suction  valves,  equal  to  or 
a  little  more  than  the  pressure  in  the  discharge  or  force  cham- 
ber above  the  discharge  valves;  and  then,  having  thus  shut  off 
communication  with  the  suction  chamber  and  opened  up  com- 

260 


THE  WATER  PLUNGERS  251 

munication  with  the  force  chamber,  to  discharge  a  quantity  of 
water  into  the  force  chamber,  equal  in  volume  to  the  cross 
section  and  length  of  stroke  of  the  plunger  itself,  or  as  nearly 
to  such  volume  as  may  be,  presumably  amounting,  in  the  best 
pumps  and  under  the  best  pumping  conditions,  to  99^  per  cent 
of  the  displacement  volume  of  the  plunger  cross  section  multi- 
plied by  the  movement  during  the  discharge  stroke. 

The  more  or  less  perfect  action  of  the  valves  and  plungers 
control  the  hydraulic  efficiency  of  the  pumping  engine,  or  in 
other  words,  determine  how  great  a  percentage  of  the  calculated 
capacity  of  the  pumps  may  be  realized  in  the  actual  work  of 
pumping  water.  In  good  practice,  the  loss  which  seems  to  be 
inevitable  to  some  extent,  in  even  the  best  machines,  amounts 
to  from  0.4  of  one  per  cent  to  1.5  per  cent  of  the  calculated  dis- 
placement. Or  putting  it  the  other  way,  the  efficiency  or  effec- 
tiveness of  the  best  water  works  pumps  varies  from  99.6  per 
cent  to  98.5  per  cent  according  to  the  design  and  proportions 
of  the  pump,  and  the  conditions  under  which  the  pumping  is 
done.  In  specifying  pumps,  it  is  good  practice  to  allow  5  per 
cent  for  slip,  leakage,  and  other  losses  when  designating  capacity 
and  sizes  of  plungers. 

In  the  matter  of  the  loss  of  displacement  all  types  and  classes 
of  modern  pumping  engines  are  covered  by  two  distinct  and 
separate  principles  of  operation,  and  under  proper  and  reason- 
able conditions,  and  proper  and  reasonable  proportions  of 
machinery  there  is  very  little  if  any  difference  in  efficiency  in 
displacement.  One  of  the  principles  of  the  operation  of 
plungers  is  embodied  in  the  performance  of  the  Worthington 
non-rotative  engine  as  originally  brought  out  about  fifty  years 
ago;  and  this  principle  is  that  of  the  complete  stoppage  and 
pause  of  the  plunger  at  the  end  of  each  stroke  and  so  permitting 
the  quiet  seating  of  the  suction  valves  and  the  complete  closing 
of  the  communication  between  the  suction  and  plunger  cham- 
bers, before  the  return  stroke  of  the  plunger  commences.  The 
other  principle  is  that  found  in  all  crank  and  fly  wheel  pump- 
ing engines,  of  the  gradual  slowing  of  the  plunger  as  the  crank 


252  PUMPING  ENGINES 

approaches  the  limit  of  its  throw  by  virtue  of  the  changing  of 
the  crank  and  connecting  rod  from  an  angle  with  each  other  to 
the  same  straight  line,  as  the  engine  reaches  what  is  known  as 
the  dead  center.  Summing  up  these  two  different  principles 
as  opposing  each  other,  the  former  probably  fills  the  pump  the 
easier,  while  the  latter  probably  picks  up  the  load  of  discharge 
the  easier;  the  total  effect  of  both  operations  of  suction  and 
discharge  working  together  so  as  to  produce  just  about  the 
same  final  effects  regarding  the  losses  in  quantity  as  shown  by 
actual  delivery  over  a  weir  as  compared  with  the  amount  of 
displacement  called  for  by  the  cross  section  and  length  of  stroke. 
A  moments  reflection  will  convince  anyone  that  perfect  dis- 
placement is  impossible,  and  even  impossible  to  calculate 
exactly;  there  is  a  certain  amount  of  compressibility  in  the 
water  as  a  practical  fact,  owing  to  the  air  which  although 
ever  so  small  in  quantity  is  nevertheless  present  in  all  water 
handled  by  water  works  pumps;  and  the  difference  in  the 
attenuating  or  expansive  effect  upon  this  air  during  suction, 
and  the  compressing  effect  upon  this  same  air  during  the  dis- 
charge, represents  a  change  in  volume  which  forever  places  out 
of  reach  of  practical  operations  that  complete  measurement  of 
discharge  which  is  comprised  within  the  expression  of  100  per 
cent.  It  is  also  impossible  to  measure  the  diameter  and  stroke 
with  absolute  exactness.  The  writer  knows  by  experience 
that  the  same  man  measuring  three  times,  or  three  men  meas- 
uring three  times,  or  either  one  or  three  men  measuring  any 
number  of  times,  will  not  always  obtain  the  same  record 
even  with  the  finest  kind  of  measuring  instruments;  and,  of 
course,  there  is  only  one  correct  measurement,  and  an  unlimited 
number  of  incorrect  measurements,  so  that  in  actual  opera- 
tions it  is  found  necessary  to  average  several  measurements 
and  agree  that  this  average  is  correct  for  purposes  of  settling 
questions  under  a  contract.  Even  the  gauging  of  plunger  dis- 
placement by  means  of  a  weir  is  not  free  from  uncertainties, 
as  the  reading,  allowances,  and  calculations  involved  in  the 
uses  of  a  weir,  with  its  crest  readings,  velocity  of  approach  of 


THE   WATER   PLUNGERS 


253 


the  water  towards  the  crest,  and  other  exquisite  refinements 
necessary  for  correctness,  and  which  often  if  not  always  have 
to  be  agreed  upon  from  averages  of  several  observers,  represent 
disturbing  factors  standing  between  the  facts  and  the  nearest 
approach  possible  thereto.  Taking  it  all  in  all  the  plunger  dis- 
placement of  a  properly  proportioned  and  adapted  pumping 
engine  is  to  be  preferred  to  a  weir  demonstration,  as  being  much 


Speed  of  Plunger 
251  ft.  per  min. 


Speed  of  Plunger 
93  ft.  per  min. 


Speed  of  Plunger 
93  ft.  per  min. 


Average  Plunger  Spe  d  160  Feet  per  Minute, 


Speed  of  Rrunger 

Crank  Pin 
251  it.  pi-r  min. 


Fig.  68.        Diagram  of  Crank  and  Plunge  Movements. 

simpler  and  having  its  factors  within  easier  reach  of  a  more 
positive  determination. 

To  illustrate  the  difference  in  plunger  speed  and  movement 
between  the  rotative  or  crank  and  fly  wheel,  and  the  non- 
rotative  or  crankless  engine,  reference  is  made  to  Fig.  68,  which 
shows  the  different  positions  of  the  crank  pin  of  a  crank  and 
fly  wheel  pumping  engine,  and  the  corresponding  positions  of 


254  PUMPING  ENGINES 

the  plunger  at  the  same  time,  disregarding  any  modifications 
which  would  be  made  by  the  angle  of  the  connecting  rod.  The 
engine  is  of  48  inches  stroke  and  making  20  revolutions  per 
minute,  which  would  give  the  crank  pin  an  angular  velocity, 
or  a  speed  around  its  circle  of  251  feet  per  minute;  found  by 
multiplying  4,  which  is  the  stroke  in  feet,  by  3.14,  which  is  the 
ratio  between  the  diameter  and  circumference  of  a  circle,  and 
multiplying  this  result  by  20  revolutions  per  minute.  The 
actual  number  of  feet  traveled  by  the  plunger  per  minute  is 
160,  found  by  multiplying  8,  which  is  the  number  of  feet  in  one 
revolution,  or  twice  the  stroke,  by  20,  which  is  the  number  of 
revolutions  per  minute. 

Now  with  the  crank  pin  half  way  between  the  two  dead 
centers,  the  speed  of  the  crank  pin  and  the  speed  of  the  plun- 
ger would  be  the  same;  but,  after  the  crank  pin  has  reached 
half  way  between  this  middle  point  and  the  dead  center,  the 
crank  pin  will  still  have  to  travel  18.94  inches  to  reach  the 
dead  center,  while  the  plunger  will  only  have  to  travel  7  inches 
to  reach  the  same  point,  which  means  that  the  crank  pin  will 
have  to  move  at  the  regular  rate  of  251  ft.  per  minute  while 
the  plunger  can  reduce  its  speed  to  93  ft.  per  minute,  a  reduc- 
tion in  the  speed  of  the  plunger  of  a  little  more  than  62  per 
cent  below  what  it  had  at  midstroke. 

When  the  crank  pin  has  again  cut  the  distance  in  half,  be- 
tween the  45  degree  point,  which  has  just  been  considered, 
and  the  dead  center,  bringing  it  within  22^  degrees  of  the  dead 
center,  its  speed  will  still  be  251  ft.  per  minute,  but  the  speed 
of  the  plunger  will  be  reduced  to  53  ft.  per  minute,  or  a  little 
more  than  80  per  cent  lower  speed  than  it  had  at  the  midstroke 
position. 

When  the  crank  pin  has  again  cut  the  angle  in  half  and 
arrived  at  a  point  11}  degrees  from  the  dead  center  its  speed 
will  still  be  251  ft.  per  minute,  while  the  speed  of  the  plunger 
will  be  reduced  to  26  ft.  per  minute,  a  reduction  in  speed  of 
more  than  89  per  cent,  practically  90  per  cent  reduction  from 
that  at  midstroke,  and  a  plunger  speed  no  doubt  very  much 


THE  WATER  PLUNGERS  255 

below  that  of  the  non-rotative  engine  plunger  at  a  correspond- 
ing point  in  the  stroke. 

Now  turning  to  the  non-rotative  or  direct  acting  pumping 
engine,  as  built  in  the  early  days  when  designed  so  as  to  reap 
all  of  the  benefits  and  advantages  of  the  system  of  pausing 
at  the  ends  of  the  strokes,  the  speed  is  taken  at  100  ft.  per 
minute  with  a  4  foot  stroke  machine,  making  12 \  "re volutions " 
per  minute.  With  a  pause  of  one  second  at  the  end  of  the 
stroke,  25  seconds  will  be  lost  each  minute,  making  it  necessary 
to  move  the  plungers  during  only  35  seconds  of  the  time  instead 
of  60  seconds  contained  in  the  minute.  This  will  give  an 
actual  plunger  speed  of  175  ft.  per  minute,  which  is  above 
the  average  speed  of  the  crank  engine  plunger,  and  nearly 
68  per  cent  of  the  highest  speed  of  the  crank  pin  as  already 
observed.  This  speed  no  doubt  continues  just  about  up  to 
the  finish  of  the  stroke  or  at  least  until  the  cushion  of  exhaust 
steam  begins  to  stop  the  pistons;  at  all  events  the  speed  of 
the  non-rotative  plunger  is  likely  somewhat  faster  near  the 
terminal  of  the  strokes  than  the  plunger  in  the  crank  machine, 
and  stops  less  gradually  than  the  latter,  but  the  pause  is  the 
saving  factor  in  the  operation. 

With  a  pause  of  1J  seconds,  the  actual  speed  would  be  266 
ft.  per  minute  while  the  non-rotative  plunger  was  really  mov- 
ing, as  there  would  be  only  22.5  seconds  in  which  to  do  the 
work  during  each  minute  of  time.  And  with  a  pause  of  only 
%  second  at  the  end  of  each  stroke,  the  actual  plunger  speed 
would  be  126  ft.  per  minute,  as  there  would  be  47J  seconds 
in  each  minute  to  get  the  motion. 

With  the  non-rotative  engine  making  128  ft.  per  minute, 
which  would  be  a  48  inch  stroke  engine  making  16  "revo- 
lutions" per  minute,  and  with  a  half  second  pause  at  the  end 
of  the  stroke,  the  actual  plunger  speed  would  be  173  ft.  per 
minute.  With  a  }  second  pause,  the  speed  would  be  213 
ft.  per  minute. 

With  the  non-rotative  engine  making  150  ft.  per  minute  with 
48  inches  stroke,  the  "revolutions"  would  be  18.75  per  minute, 


256  PUMPING  ENGINES 

and  with  a  half  second  pause  the  plungers  would  travel  at  the 
rate  of  218  ft.  per  minute;  while  the  same  engine  making  £ 
second  pauses  would  have  a  plunger  speed  of  283  ft.  actual 
travel  per  minute. 

The  speed  of  the  plunger  is  generally  given  in  terms  of  feet 
traveled  per  minute,  and  has  long  been,  and  is  yet  for  that 
matter,  a  subject  of  much  argument  and  dispute  and  mis- 
understanding. There  is  an  extremely  important  difference 
in  the  way  that  plunger  speed  is  produced,  and  this  difference 
can  be  broadly  shown  by  giving  two  ways  of  producing  any 
certain  or  desired  feet  travel  per  minute.  One  is  with  a  short 
stroke  plunger,  making  comparatively  a  good  many  strokes  per 
minute ;  and  the  other  is  with  a  long  stroke  plunger  making  com- 
paratively few  strokes  per  minute.  The  key  to  the  situation  is 
the  rate  of  opening  and  closing  of  the  pump  valves  per  min- 
ute; and  the  speed  which  gives  the  number  of  times  per  minute 
allowed  for  the  working  of  the  pump  valves,  as  determined 
by  the  best  and  most  experienced  makers,  and  as  found  in 
the  pumping  engines  which  give  the  highest  efficiency  and 
economy,  is  in  the  neighborhood  of  20  revolutions  per  min- 
ute. That  is  to  say,  in  crank  and  fly  wheel  pumping  engines 
the  rate  of  revolution  of  the  fly  wheels  are  as  given  above,  and 
in  the  direct  acting  or  non-rotative  pumping  engines,  the  cor- 
responding motions  of  the  pistons  and  plungers.  The  rates 
given  in  the  table  of  suction  valve  areas  will  be  found  to  be 
in  line  with  the  best  practice  and  the  best  results  obtained 
in  actual  work. 

Upon  the  merits  of  the  case,  so  far  at  least,  everything  is 
against  rapid  plunger  action,  that  is,  rapid  rate  of  revolution 
of  the  engine  and  frequent  reciprocation  of  the  plungers.  The 
longer  the  stroke  of  the  plungers  and  the  lower  the  number 
of  strokes  per  minute,  the  better  it  will  be  for  the  effectiveness 
and  durability  of  the  pumps;  and  this  principle  can  only  be 
carried  too  far  with  steam  machinery  at  least,  with  reference 
to  the  cost  of  the  machine  and  for  no  other  reason  apparently. 
The  records  show  that  there  is  absolutely  nothing  in  the  line 


THE  WATER  PLUNGERS  257 

of  steam  economy,  in  high  speed  in  feet  per  minute  or  in  rate 
of  revolution.  The  steam  engine  holding  the  economy  record 
to-day  makes  only  17^  revolutions  per  minute,  and  has  a  pis- 
ton speed  of  only  197  ft.  per  minute.  Its  mechanical  efficiency 
is  96  per  cent  and  its  steam  consumption  is  10.335  Ibs. 
of  steam  per  indicated  horse  power  per  hour. 

Therefore  the  logic  of  plunger  speed  in  a  pumping  engine 
is  to  make  the  engine  as  large  and  run  it  as  slowly  as  the  capi- 
tal account  will  permit,  or  until  the  interest  account  and  the 
repair  account  can  be  made  to  properly  compromise  with  each 
other.  The  steam  economy  account  may  be  safely  left  out 
of  the  question,  or  at  least  need  not  be  feared  in  going  towards 
large,  slowly  working  pumping  machinery. 

The  gas  engine  is  showing  great  promise  just  now  as  to 
economy  of  coal,  and  is  probably  worth  trying  with  a  fast 
running  pump  if  that  is  the  only  kind  of  pump  practicable 
for  it  to  operate,  but  the  pump  valves  will  doubtless  need  some 
modification  from  the  present  practice  before  the  gas  pumping 
engine  can  make  a  good  name  for  durability;  but  if  such  a 
machine  can  show  200,000,000  ft.  Ibs.  duty  as  easily  as  the 
steam  machine  can  make,  say,  120,000,000  duty,  both  with 
coal  burned  per  100  Ibs.,  then  it  will  pay  to  do  some  pump  experi- 
menting. 

In  water  works  pumping  engines  there  are  three  well  known 
forms  of  plunger  application,  the  plunger  and  ring,  the  inside 
packed  plunger,  and  the  outside  packed  plunger. 

The  plunger  and  ring  as  the  name  implies  consists  of  a  plain, 
smooth  cast  iron  plunger  working  through  a  brass  ring,  the 
internal  surface  of  the  ring  where  the  plunger  bears  being  gen- 
erally grooved  around  its  circumference,  so  as  to  provide  a 
sort  of  water  packing.  The  theory  of  the  grooved  ring  being, 
apparently,  that  whatever  water  endeavors  to  leak  past  the 
plunger  from  the  pressure  to  the  suction  end  of  the  pump  its 
compelled  to  pass  first  through  the  narrow  space  between  the 
inner  wall  of  the  ring  and  the  surface  of  the  plunger ;  then  when 
one  of  the  circular  grooves  is  reached,  the  suddenly  increased 


258  PUMPING  ENGINES 

volume  of  the  film  of  water  retards  the  flow,  and  when  the  next 
division  of  close  fitting  space  is  met  with  the  flow  must  again 
be  accelerated;  so  that  the  alternate  increase  and  decrease  in 
the  rate  of  passage  of  the  film  of  water  attempting  to  leak  past 
the  plunger  results  in  such  a  complete  retardation  of  the  water 
that  the  plunger  is  reversed  in  its  stroke  before  the  leakage 
really  has  a  fair  chance  of  actually  taking  place.  This  form 
of  plunger  is  mostly,  if  not  always,  confined  to  double  acting 
pumps,  or  pumps  taking  in  and  discharging  water  at  both 
ends  alternately;  the  records  and  experience  of  pumping  engine 
builders  indicating  that  in  fairly  clear  water,  or  water  free 
from  pronounced  grit,  such  plungers  and  rings  give  very  satis- 
factory results.  In  water  containing  fine,  smooth,  clayey 
silt,  or  a  trace  of  vegetable  slime,  this  type  of  plunger  which 
with  its  ring  is  entirely  without  means  of  adjustment,  will 
work  for  years  with  very  little  wear.  The  writer  has  seen 
and  examined  pumps  with  this  form  of  plunger  that  have 
been  working  under  favorable  conditions  during  a  period  of 
five  or  six  years,  and  has  found  the  leakage  to  be  very  insig- 
nificant. 

In  a  great  many  situations  this  type  of  plunger  makes  a 
very  good  pump,  probably  more  of  them  being  in  use  than 
any  other  form.  It  can  be  easily  and  accurately  made,  runs 
with  little  friction,  requires  no  adjustment,  and  very  little 
attention  in  fairly  clear  water  free  from  grit  in  any  consider- 
able quantities.  Its  advocates  argue  that  a  plunger  with  a 
solid,  non-adjustable  ring,  even  if  it  does  wear  some,  will  really 
waste  less  water  in  the  long  run  than  a  packed  plunger,  neg- 
lected and  not  given  proper  attention  with  reference  to  its 
being  competently  packed  and  operated;  it  being  remembered 
that  during  actual  operation  in  pumping  water,  the  plunger 
is  always  moving  in  a  direction  opposite  to  that  of  the  water 
trying  to  leak  past  it  from  the  forcing  to  the  suction  end  of 
the  pump,  which  naturally  enough  helps  to  retard  any  water 
attempting  to  pass  in  a  thin  film  between  the  surface  of  the 
plunger  and  that  of  the  ring. 


THE  WATER  PLUNGERS 


259 


Fig.  69  shows  the  general  features  of  this  type  of  plunger 
with  its  ring  and  plunger  rod. 

An  interesting  experiment  was  tried  by  the  writer  some 
years  ago  with  a  steam  fire  engine,  to  find  out  how  high  a  vac- 


Fig.  69.  — Plunger  and  Ring  Pump. 

uum  could  be  formed  and  maintained  with  a  solid  plunger  and 
ring.  The  plunger  was  of  brass  5  inches  in  diameter  and  of 
8  inches  stroke.  In  this  case  the  plunger  was  grooved  and 
the  ring  was  bored  and  then  reamed  as  smooth  as  it  was  pos- 
sible to  make  it.  The  plunger  and  the  ring  were  both  8  inches 
long,  arid  the  ends  of  both  were  even  with  each  other  when 
the  plunger  was  at  its  mid-stroke  position,  so  that  there  were 
4  inches  of  plunger  in  the  ring  at  each  end  of  the  stroke.  This 
test  was  made  to  learn  how  high  a  vacuum  could  be  formed 
so  as  to  judge  of  the  capability  of  the  engine  to  lift  water  20 
ft.  when  started  with  its  pump  and  suction  hose  entirely  empty, 
and  it  was  the  regular  practice  to  make  the  plunger  ^  of  an  inch 


260  PUMPING  ENGINES 

free  in  the  sleeve  or  ring,  with  reference  to  diameters.  Such 
an  experiment  so  far  as  known  had  never  at  that  time  been 
tried,  and  it  was  very  important  before  entering  a  competitive 
trial  that  was  at  hand  to  know  just  what  would  happen.  It 
was  quickly  demonstrated  however  that  under  perfectly  dry 
conditions,  with  the  exception  of  rubbing  a  very  little  oil  on 
the  plunger  to  prevent  cutting  before  it  got  the  water,  a  solid 
ring  and  plunger  with  a  perfectly  empty  pump  and  suction, 
would  form  and  maintain  21  inches  of  vacuum,  equivalent 
to  23.1  ft.  of  water.  As  a  result  of  the  experiment,  the  trial 
was  gone  into,  and  with  everything  empty  at  the  start,  water 
was  successfully  and  promptly  lifted  23  ft.,  the  suction  hose 
of  the  engine  strongly  resembling  the  tall  trunk  of  a  tree  in  the 
eyes  of  the  rather  anxious  builders  of  the  machine  and  the 
skeptical  spectators. 

The  inside  packed  plunger  very  strongly  resembles  the 
previously  described  plunger  in  water  works  engines,  and 
also  like  the  former  is  mostly  used  in  double  acting  pumps  of 
the  horizontal  class.  In  fact  this  construction  is  mostly  the 
same  as  the  last  mentioned  plunger,  with  the  exception  that 
instead  of  a  solid  ring  for  the  plunger  to  work  through,  a  com- 
plete stuffing  box  is  substituted,  fitted  into  the  same  position 
in  the  pump  as  the  solid  ring,  but  the  back  pump  head  must 
be  removed  for  inspection  and  packing.  It  has  long  been  a  dis- 
puted question  as  to  whether  or  not  there  is  any  advantage  in 
having  an  inside  packed  plunger  as  against  the  solid  ring  variety; 
the  argument  being,  that  in  the  case  of  the  ring  the  wear  is 
very  slow  and  its  condition  can  be  easily  known  and  remem- 
bered, coupled  with  the  certainty  that  it  can  only  change 
slowly  for  the  worse,  while  an  inside  stuffing  box  with  its 
packing  worn  out,  is  a  very  leaky  device,  and  it  requires  a 
good  deal  of  close  guessing  and  considerable  attention  to  deter- 
mine what  the  condition  of  the  packing  is,  and  to  keep  it  in 
good  order.  In  the  writer's  opinion  the  inside  stuffing  box 
is  a  very  questionable  device,  and  in  fairly  good  water  the  solid 
ring  is  to  be  preferred. 


THE  WATER  PLUNGERS 


261 


Fig.  70  shows  the  form  and  construction  of  the  inside  packed 
plunger  as  generally  employed  in  horizontal  double  acting 
pumps. 

The  outside  packed  plunger  is  considered  by  some  authorities 
as  the  perfection  of  plungers,  for  the  reason  that  leakages  can 


Fig.  70.  —  Inside  Packed  Plunger. 

be  seen  and  the  packing  is  accessible  for  adjustment  while  the 
engine  is  running  so  as  to  stop  such  leakages.  With  proper 
attention  this  is  so,  and  these  very  desirable  results  can  be 
obtained,  but  as  already  pointed  out,  in  good,  clear  water  a 
solid  ring  which  cannot  be  adjusted  or  neglected  to  its  detri- 
ment, will  leak  the  minimum  amount  of  water  for  a  long  time ; 
while  in  the  very  best  water  a  neglected  or  badly  adjusted  out- 
side packed  plunger,  even  though  right  under  the  very  nose 
of  a  careless  attendant,  may  be  allowed  to  leak  a  very  serious 
percentage  of  the  water  pumped. 

The  outside  packed  plunger  is  used  in  nearly  all  forms  of 
pumping  engines,  and  in  the  horizontal  machine  is  called  a 
"  center  packed"  plunger  because,  although  outside  packing  is 
used,  the  packing  of  the  plunger  is  accomplished  by  placing 
two  stuffing  boxes  within  the  open  space  formed  at  the  middle 
or  "center"  of  the  length  of  the  horizontal  pump  body,  one 


262 


PUMPING  ENGINES 


stuffing  box  for  each  end  of  the  pump.  Sometimes  the  stuffing 
boxes  are  placed  at  the  outer  and  inner  ends  of  the  horizontal 
pump  body,  with  a  solid  partition  at  the  middle  of  the  length 
of  the  pump,  to  divide  the  end  plunger  chambers  from  each 
other.  In  this  latter  form  the  plungers  are  put  in  at  the  outer 
and  inner  ends  of  the  pump,  and  connected  together  by  means 
of  heavy  rods  passing  along  the  outside  of  the  plunger  barrels 
from  end  to  end. 

Nearly  all  of  the  vertical,  crank  and  fly  wheel  pumping 
engines  have  single  acting  outside  packed  plungers  driven 
directly  from  the  steam  cross  heads  by  means  of  distance  rods 
connecting  these  cross  heads  and  the  heads  of  the  plungers 
rigidly  together.  There  have  also  been  made  vertical  engines 


Fig.  71.  —  Center  Packed  Horizontal  Plunger. 

in  which  the  outside  packed  plungers  have  been  of  the  center 
packed  class,  and  practically  like  the  horizontal  machine  turned 


THE  WATER  PLUNGERS 


263 


Fig.  72.  — Center  Packed  Vertical  Plunger. 


264 


PUMPING  ENGINES 


up  on  end.  Also,  there  have  been  built  outside  packed  differ- 
ential plunger  vertical  machines,  with  the  upper  half  of  the 
plungers  smaller  than  the  lower  half,  but  with  all  plungers  of 
the  outside  packed  variety,  these  differential  plungers  usually 
being  driven  by  means  of  a  plunger  rod  passing  through  a 
stuffing  box  in  the  top  of  the  upper  plunger  chamber. 
Fig.  71  shows  a  center  packed  horizontal  plunger.  Fig.  72 


Fig.  73.— Vertical  Outside  Packed 
Differential  Plunger. 


Fig.  74.— Vertical  Outside  Packed 
Single  Acting  Plunger. 


a  vertical  plunger  of  the  same  class.  Fig.  73  a  vertical  outside 
packed  differential  plunger.  And  Fig.  74  shows  a  vertical  out- 
side packed  single  acting  plunger. 


THE  WATER  PLUNGERS  265 

It  goes  without  saying  that  the  plunger  is  an  extremely 
Important  part  of  a  water  works  engine,  and  the  maintaining 
of  plungers  and  their  packing  in  proper  form  and  smoothness 
is  well  worthy  of  careful  attention  and  some  expense.  They 
should  be  made  of  close  grained  material;  most  of  them  are 
made  of  cast  iron,  and  as  hard  iron  as  can  be  worked  with  the 
tools  in  reasonable  time.  Late  practice  goes  even  so  far  as 
casting  the  plunger  in  a  chill,  and  then  after  turning  closely  to 
shape  and  dimensions,  grinding  it  to  a  finished  surface  where 
it  works  in  and  through  the  packing.  When  the  value  of  low 
friction  and  high  efficiency  is  considered,  such  refinements, 
really  adding  but  little  to  the  cost  of  the  engine,  are  worth  while 
obtaining. 

The  plungers  working  through  solid  rings  in  horizontal  pumps 
.are  usually  connected  to  the  steam  pistons  of  the  machine  by 
plunger  rods  extending  from  the  plunger  through  a  stuffing 
box  in  the  pump  head,  towards  the  steam  end,  and  connecting 
with  the  main  cross  head.  The  inside  packed,  and  the  center 
packed  plungers  are  connected  in  horizontal  pumps  the  same 
as  in  the  ring  type,  by  a  rod  through  a  stuffing  box  in  the  pump 
head,  and  so  to  the  cross  head.  The  outside  packed,  and  the 
end  plungers  in  horizontal  pumps  are  connected  together  by 
.side  rods  outside  the  pump  barrel,  and  these  rods  are  connected 
to  the  main  cross  head. 

The  outside  packed  vertical  plungers,  consisting  of  single  act- 
ing plungers;  double  acting  center  packed  plungers,  and  differ- 
ential outside  packed  plungers,  are  usually  connected  to  the 
steam  cross  heads  by  means  of  vertical  distance  rods  extending 
from  the  plunger  heads  above  the  pump  barrels,  to  the  cross 
heads  beneath  the  steam  cylinders;  these  distance  rods,  or 
plunger  rods,  passing  down  through  the  space  back  of  the 
c:anks,  between  the  cranks  and  the  main  pillow  blocks,  and 
also  in  front  of  the  cranks.  Sometimes  two  of  these  rods  are 
used,  placed  diagonally  from  each  other,  and  sometimes  four  of 
the  rods  are  used,  according  to  the  ideas  of  the  designer  and 
the  size  of  the  machine.  But  whatever  the  kind  of  plunger 


Xv^^^s, 

f  OF  THE  A 

f    UNIVERSITY   | 
V  OF  / 


266  PUMPING  ENGINES 

and  however  connected,  the  proper  idea  is  to  have  a  perfectly 
rigid  and  direct  connection  between  the  steam  pistons  and  the 
water  plungers,  and  so  to  avoid  driving  the  load  by  or  through 
moving  connections  and  joints. 

The  plunger  rods  in  horizontal  pumps  are  secured  to  the  plun- 
gers in  various  ways.  Fitted  into  a  taper  socket  in  a  hub  at  one 
end  of  the  plunger  and  keyed;  carried  through  the  length  of  the 
plunger,  with  a  shoulder  or  collar  at  one  end  and  a  large  nut 
at  the  other,  the  nut  secured  after  being  solidly  set  home,  by 
some  sort  of  a  keeper;  by  a  nut,  and  shoulder  or  collar  on  the 
rod,  the  rod  passing  through  a  heavy  partition  or  web  at  the 
middle  of  the  length  of  the  plunger. 

In  vertical  pumps  with  double  acting  or  differential  plungers, 
and  having  plunger  rods  passing  through  the  tops  of  the  pump 
barrels,  the  hub  and  key  at  the  top  of  the  plunger  are  usually 
emp1  oyed ;  while  in  vertical  pumps  having  the  plungers  passing 
out  through  stuffing  boxes  at  the  top,  the  plunger  head  is 
usually  formed  so  that  collars  and  nuts  at  the  lower  ends  of  the 
distance  or  plunger  rods  secure  the  plungers.  There  are  other 
ways  of  arranging  plunger  rods  and  connecting  them  to  the 
plungers,  more  or  less  complicated  and  more  or  less  dangerous 
in  operation,  but  the  foregoing  methods  cover  the  generally 
accepted  practice  to  which  the  great  majority  of  pumping 
engines  have  been  reduced,  and  which  are  considered  by 
different  builders  apparently  as  giving  the  best  satisfaction. 


CHAPTER   XX 
AIR   CHAMBERS 

THE  water  is  delivered  into  the  force  chamber  above  the 
discharge  valves  from  the  plunger  barrel  in  absolutely  sepa- 
rate quantities  at  each  displacement,  of  the  plunger  or  plun- 
gers. And,  in  the  absence  of  any  equalizing  device,  here 
would  be  as  many  distinct  shocks  in  the  water  column  as  there 
are  strokes  in  the  operation  of  the  pump.  But  these  distinct 
strokes  of  the  plunger  can  be  blended  into  a  continuous  and 
nearly  uniform  stream  by  the  employment  of  a  large  vessel  or 
chamber,  placed  in  a  suitable  location  above  the  discharge 
line  of  the  pump,  the  upper  portion  of  this  vessel  or  air- 
chamber  being  charged  with  or  containing  ordinary  atmospheric 
air  compressed  to  a  tension  like  that  of  a  spring,  equal  to  the 
pressure  of  the  water  delivered  by  the  main  pumps.  It  is  the 
great  elasticity,  or  quality  of  instant  compression  and  expan- 
sion, possessed  by  the  air  contained  within  the  air  chamber 
to  suit  the  variations  in  pressure  of  the  water  being  delivered 
by  the  plungers,  which  makes  the  air  chamber  such  a  valuable 
detail  to  a  pump.  There  are  many  different  arrangements 
of  plungers,  with  reference  to  the  different  times  and  order 
in  which  they  deliver  the  water  through  the  discharge  valves 
into  the  force  chamber;  and  there  is  a  wide  difference  between 
the  regular  or  irregular  action  and  effect  in  plungers  in  doing 
such  work.  But  there  is  no  water  works  pump  working  with 
plungers,  delivering  water  into  long  lines  of  pipes  or  mains, 
however  uniform,  blended,  and  regular  the  actual  plunger 
deliveries  may  be  by  virtue  of  the  mechanical  relation  and 
arrangement  of  such  plungers,  but  what  the  smoothness  of  the 
flow  will  be  greatly  improved  by  the  use  of  a  proper  air  chamber. 

267 


268  PUMPING  ENGINES 

The  extreme  amount  of  irregularity  would  be  produced 
by  one  single  acting  plunger  taking  in  the  water  at  one  stroke 
and  discharging  it  at  the  next;  but  the  spasmodic  work  result- 
ing from  the  use  of  such  a  plunger  may  be  reduced  to  a  very 
nearly  uniform  stream  by  a  well  formed  and  appropriately 
located  air  chamber  near  the  delivery  nozzle  of  the  pump.  One 
double  acting  plunger  or  two  single  acting  plungers  would 
naturally  start  the  flow  more  steadily  than  one  of  the  single 
acting  form.  Two  double  acting  plungers  with  their  strokes 
blended  as  in  the  non-rotative  or  in  the  90  degrees  crank  and  fly 
wheel  engine,  would  be  an  improvement  on  one  double  acting. 
Four  double  acting  plungers,  or  pistons,  with  the  crank  pins 
at  135  degrees  and  the  center  lines  of  the  opposite  sides  of  the 
engine  at  90  degrees,  as  in  the  older  type  known  as  the  Holly 
quadruplex,  would  give  8  impulses  to  the  water  column  at 
each  revolution  of  the  wheel,  and  would  give  a  still  greater 
uniformity  of  delivering  pressure  than  the  90  degrees  crank 
engine.  Three  single  acting  plungers,  with  the  crank  pins 
set  at  angles  of  120  degrees  around  the  circle,  will  give  a  very 
good  result  in  close  uniformity  of  flow. 

But  with  the  best,  and  with  all,  of  the  different  number  and 
arrangements  of  plungers,  the  necessity  for  the  air  chamber 
exists  where  smooth  work  and  high  economy  are  desired  in  a 
regular  water  works  pumping  plant.  The  service  which  the 
air  chamber  performs  is  to  receive  the  impulses  of  or  pulsa- 
tions given  out  by  the  plunger  deliveries,  against  its  air  cushion, 
and  thus  take  up  by  an  elastic  medium  what  would  otherwise 
be  a  decided  series  of  shocks  within  the  mass  of  water  and 
against  the  sides  of  the  valve  chambers  and  pipes.  Or,  in 
other  words,  without  the  air  chamber  the  motion  of  the  water 
would  be  intermittent;  but  as  the  velocity  of  the  water  on 
entering  the  air  chamber  is  more  than  on  leaving  it,  the  level 
of  the  water  therein  rises  above  the  outlet  and  compresses 
the  air  which  fills  the  air  chamber.  Hence,  whenever  a  plun- 
ger stops,  the  air  thus  compressed,  reacting  upon  the  water, 
forces  it  out  during  the  momentary  stoppage  and  thus  keeps 


AIR  CHAMBERS  269 

a  constant  flow.  The  object  sought  in  pumping  water  is  to 
produce  a  steady  uniform  flow  with  the  least  change  in  pres- 
sure practicable;  but  the  pump  deliveries  being  from  the  nature 
of  the  machine  intermittent  and  pulsating,  on  account  of  sepa- 
rate and  measured  quantities  being  repeatedly  sent  into  the 
force  chamber  at  different  rates  of  motion,  and  at  a  rate  of 
flow  completely  at  variance  with  the  uniformity  sought  in  the 
force  main,  the  water  pressure  in  the  absence  of  the  air  cham- 
ber would  be  suddenly  increased  for  an  instant  at  a  time,  and 
in  effect  a  sudden  and  repeated  increase  in  the  velocity  of 
flow  in  the  force  main  at  the  pump  would  become  necessary. 
The  air  chamber,  however,  when  properly  located,  by  means 
of  its  elastic  cushion,  safely  receives  the  impact  of  the  sudden 
rush  of  water  from  the  pumps,  and  the  attempted  shock  or 
rise  of  the  water  pressure  is  mostly  expended  in  a  slight  com- 
pression of  the  confined  body  of  air,  and  the  surplus  for  the 
moment  above  what  is  required  to  keep  up  the  constant  flow 
in  the  main,  is  retained  within  the  air  chamber  just  for  the 
instant  necessary  to  permit  of  the  uniform  distribution. 

In  the  practical  construction  of  water  works  engines  it  is 
not  always  possible  to  locate  the  air  chamber  at  the  best  point 
in  the  design  itself,  and  convenience  in  the  supporting  of  the 
various  parts  of  the  machine  often  takes  precedence  over  any 
particular  consideration  of  the  matter  of  the  air  chamber  being 
located  so  as  to  receive,  in  the  best  and  most  effective  man- 
ner, the  comparatively  rapid  deliveries  and  consequent  pul- 
sations of  the  plunger  energy.  It  is  very  likely  that  the 
thought  devoted  to  the  air  chamber  is  not  so  serious  or  abun- 
dant as  it  should  be;  but  rather,  the  idea  most  prevalent  is 
that  after  some  of  the  other  details  have  been  arranged  with 
reference  to  making  a  reliable,  economical,  and  durable  machine 
of  moderate  or  low  cost,  some  of  the  parts  are  made  conven- 
ient for  air  chamber  purposes;  and  this  of  course  magnifies 
the  importance  of  the  plunger  arrangement,  on  the  principle 
that  the  less  effective  the  air  chamber,  the  more  the  plunger 
action  must  be  blended  to  secure  uniformity  of  flow. 


270  PUMPING  ENGINES 

This  idea  of  undesirable  plunger  arrangement  and  insuffi- 
cient air  chamber  combined,  was  clearly  illustrated  in  the 
experience  of  the  writer  several  times  during  the  past  few 
years,  the  opportunities  for  such  observations  not  being  any 
too  plenty  under  actual  water  works  conditions  and  service. 
In  three  pronounced  cases  the  engine  was  of  the  two  plunger 
class  of  the  crank  and  fly  wheel  type;  two  single  acting  plun- 
gers, with  the  crank  pins  directly  opposite  each  other,  or  at 
180  degrees.  One  engine  was  on  direct  service  with  a  closed 
system  of  pipes  having  no  stand  pipe  or  reservoir.  There 
had  been  some  complaints  about  noises  in  the  house  faucets 
within  the  high  service  district  supplied  by  this  engine,  and 
a  call  at  a  number  of  the  houses  resulted  in  the  disclosure  of 
the  fact  that  every  stroke  and  revolution  of  the  engine  could 
be  counted  very  readily  at  the  kitchen  faucet,  by  the  shocks 
or  pulsations  in  the  water,  not  taken  up  or  obviated  by  appro- 
priate air  chamber  capacity  and  location,  although  the  engine 
itself  apparently  had  a  fair  allowance  of  space  above  the  dis- 
charge valves  for  entrapping  air  enough  for  a  pump  cushion. 

In  the  next  case,  the  plungers  were  also  opposite  each  other 
in  motion  with  the  crank  pins  at  180  degrees,  but  this  engine  did 
its  pumping  into  the  distribution  of  the  entire  city;  and  the  sur- 
plus over  and  above  the  consumption  went  into  the  reservoir, 
the  city  distribution  being  located  between  the  pumping  station 
and  the  reservoir.  After  the  starting  of  the  new  engine,  which 
is  the  one  referred  to,  and  which  was  the  wrong  kind  of  an 
engine  for  the  service,  many  complaints  began  to  come  in  from 
the  water  consumers;  and  there  was  no  doubt  whatever  of  the 
shocks  and  pulsations  within  the  mains  and  service  pipes.  After 
the  matter  was  carefully  looked  over  and  the  conditions  noted, 
a  large  air  chamber  was  placed  just  inside  the  walls  of  the  pump- 
ing station  and  connected  with  the  force  main  outside  of  the 
check  valve.  The  force  main  was  24  inches  in  diameter;  the 
air  chamber  made  of  steel  plate  was  36  inches  in  diameter  by 
15  feet  in  height;  the  bottom  of  the  air  chamber  being  contracted 
to  12  inches  where  it  was  joined  to  the  force  rrain.  The  result 


!         AIR  CHAMBERS  271 

was  most  satisfactory.  The  pulsations  gave  no  further  trouble, 
and  so  far  as  the  consumers  were  concerned  ceased  to  exist, 
although  there  was  no  doubt  still  remaining,  some  traces  of 
the  rather  positive  action  of  two  single  acting  plungers  upon 
the  water  column.  % 

The  third  was  that  of  an  engine  pumping  into  a  reservoir 
through  a  force  main  and  with  no  connection  whatever  with 
the  consumers.  There  were  of  course  no  complaints,  but  a 
person  standing  upon  the  ground  at  the  reservoir  directly  over 
the  force  main  where  it  entered  the  basin,  could  distinctly 
count  the  strokes  of  the  plungers;  the  engine  was  about  2,000 
feet  away  from  the  reservoir  and  was  of  the  two  plunger  class 
with  crank  pins  180  degrees  apart. 

The  writer  is  not  aware  that  any  remedy  was  ever  applied 
in  the  first  and  third  cases  above  mentioned,  but  there  is 
scarcely  room  for  doubting  that  ample  air  chamber  capacity 
properly  designed  and  located  would  have  greatly  reduced  the 
pulsations  in  both  cases. 

In  a  water  works  plant  the  greatest  use  of  the  air  chamber  is 
really  more  on  account  of  the  distributing  mains  and  pipes  than 
of  the  pumping  machinery,  although  the  refinements  of  steam 
economy  are  found  along  the  lines  of  smooth  action,  but  no 
doubt  the  ordinary  methods  of  construction  furnish  sufficient 
cushioning  effects  for  the  engine  itself.  Therefore  the  location  of 
an  air  chamber  outside  of  the  engine  construction  should  be  made 
with  reference  to  the  force  main  where  it  leaves  the  building  or 
approximately  at  that  point;  and  where  the  air  chamber  is 
applied  for  this  purpose,  its  dimensions  should  conform  to  the 
dimensions  of  the  pipe  with  reference  to  it's  greatest  probable 
capacity.  There  are  no  hard  and  fast  rules  concerning  the 
size  and  capacity  of  such  air  chambers,  but  a  proportion  prob- 
ably as  good  as  any,  and  which  experience  shows  at  least  so  far 
will  be  sufficient  to  correct  to  an  acceptable  degree  the  pulsa- 
tions of  two  single  acting  plungers,  likely  the  worst  condition 
to  be  met  with,  would  be  as  follows : 

The  inside  diameter  of  the  force  main  where  it  leaves  the 


272 


PUMPING  ENGINES 


building  is  taken  as  the  basis  for  the  dimensions  of  the  air 
chamber. 

Then  one  and  a  half  times  (1.5)  the  diameter  of  the  force 
main  will  be  the  inside  diameter  of  the  air  chamber : 

And  seven  and  a  half  times  (7.5)  *the  diameter  of  the  force 
main  will  be  the  height  of  the  air  chamber : 

And  half  the  diameter  (0.5)  of  the  force  main  will  be  the 
diameter  of  the  opening  into  the  bottom  of  the  air  chamber. 

Such  air  chambers  should  be  constructed  along  the  lines  of 
first  class  boiler  work  and  made  of  steel  plates;  the  bottom  where 
it  changes  from  its  inlet  opening  to  the  full  size  of  the  air  cham- 
ber could  be  made  of  cast  iron  for  the  smaller  ones,  and  of 
cast  steel  for  the  larger  ones;  although  if  desired  the  bottom  could 
be  formed  of  the  steel  plate  similar  to  the  flanging  of  a  boiler 
head,  the  top  in  all  cases  to  be  of  steel  plate  like  the  top  of  a 
steam  boiler  dome. 

With  this  rule  an  air  chamber  would  be  according  to  the  fol- 
lowing table : 


DIAMETER  OF 
FORCE  MAIN, 
INCHES. 

DIAMETER  OF 

THE   AIR 

CHAMBER, 
INCHES. 

HEIGHT  OK  THE 
AIR  CHAMBER, 
FEET. 

OPENING  IN  THE 
BOTTOM  OF  THE 
AIR  CHAMBER, 
INCHES. 

16 

24 

10.0 

8 

20 

30 

12.o 

10 

24 

36 

15.0 

12 

30 

45 

18.8 

15 

36 

54 

22.5 

18 

48 

72 

30.0 

24 

The  strength  of  such  air  chambers  would  have  to  be  calcu- 
lated according  to  steam  boilers  for  thickness  of  plates,  or  as 
follows : 

Multiply  the  pressure  to  be  carried  in  the  air  chamber  by 
the  diameter  in  inches,  and  divide  by  2,  and  this  will  give  the 
bursting  strain  against  the  metal  for  one  inch  in  length;  then 
divide  this  result  by  one  tenth  of  the  tensile  strength  of  the 
steel  plate  per  square  inch,  and  the  result  will  give  the  proper 
thickness  of  plate  to  be  used. 


AIR  CHAMBERS  273 

What  thickness  would  be  necessary  in  the  steel  plates  for  an 
air  chamber  36  inches  in  diameter  to  hold  a  pressure  of  100 
Ibs.  per  square  inch? 

100  X  36  =  3,600,  which  divided  by  2  gives  1,800  as  the 
strain  put  on  each  inch  of  length  of  the  air  chamber,  and  what 
one  inch  will  stand  it  will  all  stand.  Good  steel  plate  will 
stand  60,000  Ibs.  per  square  inch  of  section  before  parting,, 
but  for  safety  a  margin  of  90  per  cent  is  allowed,  reducing  the 
actual  strength  reckoned  upon  to  6,000  Ibs.  per  square  inch. 
Then  1,800  divided  by  6,000  will  give  three  tenths  (0.3)  of  an 
inch  as  the  proper  thickness  of  the  plates  for  making  the  air 
chamber.  This  may  seem  like  a  liberal  margin  for  safety,  but 
the  writer  has  seen  water  ram  in  mains  send  the  pressure  up 
from  the  normal  pressure  of  110  to  the  ram  pressure  of  350  Ibs. 
per  square  inch,  which  would  leave  a  margin  for  safety  of  only 
2.85  to  1  with  60,000  steel  and  a  thickness  of  0.3  of  an  inch 
for  an  air  chamber  36  inches  in  diameter; 

The  mention  of  water  rams  and  shocks  in  force  mains  natu- 
rally brings  forward  the  subject  of  check  valves,  which  are 
generally  placed  in  the  line  of  the  force  main  just  outside  of 
the  main  pumps  of  a  water  works  engine.  Check  valves  at 
times  have  their  uses,  but  cannot  be  looked  upon  with  favor 
under  heavy  pressure  and  with  long  force  mains,  where  an 
extended  "slug"  of  water  is  in  motion  away  from  the  engine, 
for  the  reason  that  there  is  plenty  of  evidence  that  such  mains 
have  been  caused  to  leak  and  even  burst  open  by  the  reaction 
of  the  water  column  when  the  engine  has  been  stopped  a  little 
too  quickly,  and  the  water  column  in  reversing  finds  a  sud- 
denly closed  check  valve  against  it  instead  of  the  air  chamber 
cushion  which  ought  to  be  there  for  just  such  occasions. 

In  two  plants  in  different  places,  recently  enlarged,  one 
with  a  force  main  14  miles  long,  and  the  other  about  7  miles 
long,  there  had  been  shown  considerable  distress  in  the  matter 
of  joints  of  the  force  main  persistently  leaking,  with  occasion- 
ally a  break  in  the  main.  At  different  times  and  of  course 
without  any  connection  with  each  other  beyond  the  facts  of 


274  PUMPING  ENGINES 

similar  conditions  existing,  these  troubles  took  place  from 
time  to  time,  when  the  idea  occurred  to  take  out  the  internal 
deta'ls  of  the  check  valve  at  one  of  these  plants,  leaving  noth- 
ing but  the  shell,  and  making  of  what  remained  of  the  check 
valve  really  a  portion  of  the  main.  This  gave  the  force  main 
the  benefit  of  the  air  chambers  of  the  pumping  machinery  to 
react  upon,  and  the  results  were  most  beneficial,  in  fact  so  much 
so  that  when  a  new  and  large  additional  pumping  engine  was 
installed,  the  check  valve  was  omitted  from  the  outfit;  but 
there  is  a  regular  stop  valve  which  can  be  closed  when  neces- 
sary and  seems  to  answer  all  purposes. 

With  the  om'ssion  of  the  foot  valve  also,  this  addition  to  the 
plant  above  referred  to,  seems  to  be  flying  in  the  face  of  all  pre- 
cedent, but  in  this  as  in  other  plants  it  has  been  fully  demon- 
strated that  under  fairly  good  conditions  easily  obtainable  in  a 
great  majority  of  cases,  there  is  no  need  whatever  of  either 
foot  or  check  valves  being  attached  to  pumping  engines.  Now 
both  of  the  above  mentioned  plants  have  discarded  both  foot 
and  check  valves,  and  nothing  short  of  coercion  will  bring 
them  back  again  into  use.  It  apparently  requires  some  little 
courage  to  depart  from  such  a  long  followed  practice,  but  it 
would  seem  as  though  all  of  the  well  known  characteristics 
of  water  under  pressure  favor  the  omission  of  check  valves, 
which  change  certainly  gives  the  force  main  the  full  benefit 
of  the  air  chambers  of  the  engines.  If  a  check  valve  is  used 
for  any  reason,  there  should  be  a  liberal  air  chamber  attached 
to  the  main  outside  of  such  a  check  valve. 


CHAPTER   XXI 

STEAM   PISTONS 

IT  hardly  seems  necessary  to  call  attention  to  the  very  great 
importance  of  the  steam  pistons  in  a  pumping  engine,  or  in 
any  other  sort  of  steam  engine  for  that  matter ;  but  it  is  doubt- 
ful if  Denis  Papin  had  any  idea  of  the  importance  of  the 
steam  piston  and  the  figure  it  was  destined  to  cut  in  the  world 
when  he  conceived  the  idea  so  many  years  ago.  The  piston 
is  simply  a  flat  disc  or  plate  with  its  edges  bearing  against 
the  interior  of  the  cylinder  walls,  and  moving  to  and  fro,  back- 
ward and  forward,  or  up  and  down  as  the  case  may  be;  im- 
pelled or  driven  by  the  excess  of  steam  pressure  brought  to  bear 
fiist  against  one  side  and  then  against  the  other  side,  by  the 
alternate  admission  and  exhaust  of  the  steam  by  means  of 
the  valves  and  their  mechanism. 

There  are  two  great  things  desired  of  a  steam  piston:  To 
move  with  the  least  possible  friction,  and  to  keep  the  steam 
from  leaking  past.  It  requires  very  little  pressure  of  the 
packing  rings  against  the  cylinder  to  prevent  leakage,  and  it 
is  a  great  mistake  to  endeavor  to  prevent  leakage  by  setting 
the  rings  out  tight  against  the  cylinder  walls.  If  a  piston 
cannot  be  prevented  from  leaking  by  a  very  moderate  press- 
ure of  the  packing,  or  with  very  light  springs  to  hold  the  pack- 
ing out,  then  there  is  something  radically  wrong  with  the 
make-up  or  adjustment  of  the  piston  and  its  rings.  A  mo- 
ment's consideration  will  show  that  there  is  no  pressure  or 
tendency  under  proper  conditions  of  design  and  construction, 
that  will  tend  to  press  the  rings  towards  the  center  of  the  cylin- 
der; but  it  will  be  shown  that  whatever  pressure  there  is  will 
tend  to  hold  the  rings  in  the  position  which  the  pressure  hap- 

275 


276  PUMPING  ENGINES 

pens  to  find  them  in  when  the  steam  enters  the  cylinder.  Then 
if  the  cylinder  has  been  bored  smoothly  and  truly,  all  there 
is  necessary  for  the  springs  to  do  is  to  maintain  the  packing 
rings  against  the  cylinder  walls  with  just  as  little  force  as  will 
keep  them  there;  and  this  required  amount  of  force  is  very 
much  less  than  is  often  produced  by  unnecessary  and  thought- 
less setting  out  of  the  rings  and  springs. 

The  types  and  styles  of  pistons  and  their  packings  are  many 
and  various,  — heavy  rings,  light  rings,  broad  and  narrow 
rings,  continuous  rings  with  a  single  joint,  rings  in  segments 
or  sections,  rings  with  all  kinds  of  cuts  and  laps,  and  with 
almost  every  kind  and  shape  of  spring.  Pistons  with  one, 
two,  three,  and  even  up  to  five  rings  have  been  designed  and 
made;  and  the  working  steam  admitted  behind  the  rings  has 
been  used  to  take  the  place  of  metal  springs.  In  fact,  it  seems 
as  though  about  all  of  the  possible  changes  and  combinations 
in  this  line  that  could  be  made  to  perform  the  office  of  a  steam 
engine  piston,  have  been  tried.  And  although  a  few  special 
cases  have  seemed  to  demand  special  arrangements  and  de- 
tails, the  piston  which  is  used  in  the  most,  in  the  largest,  and 
in  the  most  economical  pumping  engines,  is  the  plain  cast 
iron  piston  with  a  single  cast  iron  packing  ring  with  one  cut 
in  its  circumference.  This  ring  is  made  nearly  square  in  sec- 
tion, that  is  nearly  as  thick  as  it  is  broad,  and  is  held  out  against 
the  cylinder  walls  by  a  number  of  light  steel  springs  without 
adjustment.  The  springs  simply  squeeze  into  place  around 
in  the  annular  space  between  the  back  of  the  packing  ring 
and  the  bottom  of  the  groove  into  which  the  ring  is  carefully 
although  not  very  tightly  fitted.  The  joint  where  the  ring 
is  cut  to  make  it  self-adjusting  and  elastic,  is  closed  by  what 
is  known  as  a  keeper,  which  is  a  sort  of  small  flanged  block 
generally  made  of  brass,  fitted  back  of  the  ring,  so  that  the 
flanges  of  this  block  fit  flush  with  the  ring  surface,  into  depres- 
sions cut  into  the  surfaces  of  the  ring  which  bear  against  the 
piston  head  and  follower.  This  keeper  or  block  forms  a  steam 
tight  joint,  and  is  held  in  place  by  one  of  the  springs  back  of 


STEAM  PISTONS 


277 


the    ring,    or   sometimes   by   one   of   the  ends  of  two  of   the 
springs. 

Perhaps  as  good  a  way  as  any  to  convey  ideas  upon  the 
subject  of  steam  pistons  for  water  works  pumping  engines,  is 
to  describe  several  sizes  of  pistons  for  both  horizontal  and  ver- 
tical engines;  and  therefore  reference  is  made  first  to  Fig.  75, 
representing  a  16  inch  piston  for  a  horizontal  cylinder. 


Fig,  75.  —  Steam  Piston  16  inches  in  Diameter. 

This  piston  consists  of  a  main  piston  head  a ;  a  bull  ring  br 
which  accurately  fits  over  a  part  of  the  piston  head  and  helps 
to  support  the  weight  of  the  piston  in  the  cylinder;  two  pack- 
ing rings  cc;  and  a  follower  d;  all  of  cast  iron.  The  piston  heacf 
is  snugly  fitted  to  a  tapered  end  on  the  machinery  steel  piston 
rod  e,  and  is  sometimes  ground  into  place  on  the  rod;  it  is  held 
in  place  by  a  nut  on  the  end  of  the  rod.  The  bull  ring  and  the 
packing  rings  are  slipped  into  place  and  secured  by  the  fol- 
lower, which  closes  the  end  of  the  piston  and  is  secured  by  & 
follower  bolts  f  inch  diameter  and  2|  inches  long  under  the 
head.  The  bull  ring  is  T-shaped  insection,  and  with  the  addi- 


278  PUMPING  ENGINES 

tion  of  the  edges  of  the  follower  and  piston  head,  gives  ample 
wearing  surface  for  carrying  the  weight,  which  is  so  distributed 
as  to  bring  the  pressure  per  square  inch  of  bearing  surface 
down  to  a  very  low  figure,  in  this  piston  not  more  than  10  Ibs. 
per  square  inch  of  actual  bearing  or  riding  surface.  The  pack- 
ing rings  are  two  in  number,  f  inch  thick  and  with  one  inch 
face  where  they  bear  against  the  cylinder  bore.  This  piston 
is  of  such  moderate  dimensions  that  springs  back  of  the  rings 
are  not  needed,  the  rings  themselves  being  made  so  as  to  con- 
tain a  certain  amount  of  the  spring  effect  by  the  following 
treatment : 

The  packing  ring  which  is  cast  continuous,  and  with  con- 
siderable stock  to  be  taken  off  in  finishing,  is  first  turned  to  a 
diameter  of  IG^  inches  outside,  and  15 J  inches  inside.  Then 
the  ring  is  cut,  and  a  piece  1-&  inches  long  is  removed  from  the 
circumference.  Then  the  ring  is  compressed  until  the  ends 
are  brought  together,  and  is  turned  to  fit  the  16  inch  cylinder ; 
this  will  make  the  finished  ring  when  released  from  the  com- 
pression which  it  is  placed  under  for  the  purpose  of  turning, 
16J  inches  diameter  outside,  which  when  sprung  into  the 
cylinder  bore,  will  maintain  a  very  satisfactory  bearing  against 
the  cylinder  walls.  The  writer  has  used  this  self -springing  ring 
in  pistons  as  large  as  25  inches  diameter  in  condensing  cng'ncs 
without  the  aid  of  any  steel  springs,  or  any  springs  aside  from 
the  tendency  of  the  ring  itself  treated  as  above  described;  in 
rings  as  largo  as  25  inches,  however,  an  additional  ring  inside  of 
the  wearing  ring,  made  with  the  spring  effect  as  well,  will  make 
a  better  piston. 

There  are  two  short  steel  pins  tightly  driven  into  holes  which 
are  drilled  in  the  bull  ring,  for  holding  the  packing  rings  in  the 
same  relative  position  to  each  other  and  to  the  bull  ring,  and 
preventing  the  cuts  in  the  rings  coming  opposite  each  other. 
There  are  also  two  f  inch  tapped  holes  in  the  bull  ring  for 
screwing  in  eye-bolts  for  taking  out  the  ring;  two  of  the  follower 
bolt  holes  through  the  follower  are  tapped  one  inch,  for  screwing 
in  draw  bolts ;  and  there  are  two  f  inch  tapped  holes  in  the 


!     STEAM  PISTONS  :>79 

piston  head  for  screwing  in  draw  or  saddk    bolts  when  it  is 
desired  to  take  out  the  piston. 

Fig.  76  illustrates  a  23  inch  steam  piston  somewhat  of  the 
same  type  as  the  16  inch,  but  in  this  one  steel  springs  are  used 
for  holding  out  the  packing  rings  against  the  cylinder  walls. 
The  piston  consists  of  a  piston  head  /,  the  follower  g,  the  bull 


Fig.  76.  — Steam  Piston  23  inches  in  Diameter. 

ring  h,  and  the  packing  rings  ii,  all  of  cast  iron.  In  this  piston 
there  are  four  centering  or  adjusting  screws  /,  for  adjusting  the 
center  of  the  piston  into  its  proper  place  when  from  wear  or 
any  other  cause  it  may  be  necessary  or  desirable.  The  piston 
head  is  secured  on  to  the  taper  near  the  end  of  its  rod  by  a  nut 
in  the  usual  manner;  the  bull  ring  is  made  with  a  loose  fit  on 
the  piston  head  and  is  centered  and  secured  in  its  position  by 
the  four  adjusting  screws  already  mentioned,  these  screws 


280  PUMPING  ENGINES 

being  provided  with  lock  nuts;  the  bull  ring  is  of  the  same 
T-shaped  section  as  in  the  16  inch  piston,  and  also  helps  with 
the  piston  and  follower  edges  to  carry  the  weight;  the  packing 
rings  are  separated  by  the  edge  of  the  bull  ring,  and  immediately 
back  of  the  packing  rings  and  between  them  and  the  bull  ring 
are  located  a  series  of  twenty-two  light  steel  springs  for  hold- 
ing out  the  packing  rings;  the  follower  fits  closely  on  the  outer 
part  of  the  piston  head,  holds  the  bull  ring  and  packing  rings 
in  place,  and  is  itself  secured  by  eight  follower  bolts,  J  inch 
diameter  and  2}  inches  long  under  the  heads. 

There  are  twelve  equally  distant  lugs  formed  on  the  inside 
of  each  packing  ring  for  keeping  the  springs  in  place,  eleven 
springs  for  each  ring,  one  of  the  spaces  being  used  for  placing 
the  cut  in  the  ring,  and  for  accommodating  lugs  and  pins  for 
keeping  the  rings  in  proper  relation  to  each  other;  the  packing 
rings  are  J  inch  thick  and  If  inches  broad.  There  are  the  usual 
various  sized  holes  tapped;  for  eye-bolts,  withdrawing  bolts, 
and  saddle  for  handling  the  piston,  follower,  and  rings. 

These  two  sizes  illustrate  a  very  good  form  of  steam  piston, 
especially  for  horizontal  cylinders;  and  this  general  type  is 
sometimes  made  without  a  bull  ring,  but  with  two  packing 
rings  rather  thin  in  proportion  to  width,  with  their  inner  edges 
meeting  together,  and  they  are  backed  by  one  broad  ring  cover- 
ing the  entire  backs  of  both  packing  rings;  the  springs  are  placed 
inside  the  broad  ring  and  are  usually  supported  on  studs  with 
lock  nuts  for  adjusting  the  springs.  This  latter  form  makes 
a  dangerous  piston  in  incompetent  hands,  as  they  are  likely 
under  such  circumstances  to  get  set  out  hard  enough  to  make 
a  great  deal  of  friction,  and  even  score  the  surface  of  the  cylinder. 

This  three  ring  class  of  piston  with  broad  wearing  or  packing 
rings  is  sometimes  made  for  horizontal  cylinders,  with  solid 
supports  for  the  lower  third  of  the  circle,  and  is  provided  with 
springs  for  the  upper  two  thirds,  the  lower  or  solid  portion 
being  adjustable  for  centering  the  piston  after  wear  has  taken 
place,  the  springs  sometimes  made  adjustable  and  sometimes 
not;  but  the  general  idea  of  the  device  is  to  provide  a  piston  in 


STEAM  PISTONS 


281 


a  horizontal  cylinder  which  as  it  must  ride  on  the  cylinder  sur- 
face in  any  event,  needs  no  bottom  adjustment  beyond  that 
due  to  wear,  and  whatever  elasticity  is  needed  better  be  pro- 
vided in  the  upper  sections  of  the  circle.  When  in  competent 
hands  this  form  of  piston  is  very  satisfactory,  requires  but 
little  attention,  and  wears  well;  it  is  easy  on  the  cylinder,  and 
altogether  makes  a  very  good  piston. 

Fig.  77  shows  an  entirely  different  type  of  piston.     It  is  30 
inches  in  diameter,  12  inches  deep,  and  this  particular  piston 


Fig.  77.  —  Steam  Piston  30  inches  in  Diameter. 

is  for  the  high  pressure  cylinder  of  a  vertical  triple  expansion 
pumping  engine,  but  can  be  used  for  any  other  vertical  cylinder 
of  this  diameter,  as,  for  example,  a  vertical  cross  compound 
engine.  It  is  made  of  cast  iron,  and  in  this  case  is  solid  so  as 
to  aid  in  giving  the  necessary  weight  to  the  moving  parts  of 
the  engine  with  reference  to  balancing  a  portion  of  the  pressure 
of  the  water  column,  usual  in  engines  of  this  type. 

The  packing  is  of  the  single  ring  variety,  made  with  one  cut 
and  provided  with  a  keeper  for  filling  the  gap,  as  already  ex- 


282  PUMPING  ENGINES 

plained.  There  is  only  the  piston  head,  one  packing  ring, 
and  a  follower;  the  follower  held  in  place  by  8  tap  bolts,  1£ 
inches  diameter  and  3  inches  long  under  the  heads.  The  rod 
is  made  parallel  and  a  tight  fit  in  the  piston  head,  the  collar 
also  fitting  into  a  socket,  and  the  rod  secured  by  a  large  nut 
securely  sent  home.  It  will  be  noted  that  the  corners  of  the 
rod  at  the  junction  with  the  collar  are  made  with  fillets  so  as 
to  avoid  possible  tendencies  to  fracture  at  this  point. 

The  follower  is  fitted  with  great  care,  with  solidity  and 
security  in  view;  the  upper  part  of  the  follower  fits-  the  top  of 
the  piston  head,  and  is  recessed  at  the  upper  corner  of  the  head, 
and  again  fits  for  a  short  distance  just  above  the  packing  ring; 
this  makes  accurate  and  solid  work  and  at  the  same  time  makes 
the  follower  easy  to  get  on  and  off  the  piston.  The  packing 
ring  is  placed  within  a  space  but  a  trifle  deeper  than  its  own 
thickness  so  as  to  keep  it  close  to  its  work  at  all  times,  and 
prevent  its  being  driven  in  by  pressure  when  coming  over 
the  counter  bore  at  the  ends  of  the  stroke,  as  has  happened 
to  packing  rings  at  different  times,  causing  mysterious  noises 
difficult  to  locate;  and  by  way  of  illustrating  this  point,  the 
writer  recalls  a  very  curious  experience  in  this  line  as  follows: 

A  new  large  straight  condensing  engine  had  been  built  and 
installed  by  a  concern  which  although  doing  the  very  best 
of  work,  had  not  had  very  much  experience  in  large  engines. 
This  engine  looked  extremely  well,  worked  smoothly  so  far 
as  bearings  and  connections  were  concerned,  produced  beauti- 
ful indicator  diagrams,  and  was  altogether  a  very  creditable 
turn-out  for  the  shop  that  built  it.  But,  just  after  turning 
each  center,  top  and  bottom,  there  was  a  loud  thump  or  blow, 
which,  although  evidently  not  doing  any  particular  damage 
so  far  as  could  be  seen,  was  most  distressing  to  hear,  and  most 
annoying  to  the  builders  and  the  buyer.  Besides  this,  the 
steam  economy  was  not  as  good  as  it  should  have  been,  and 
driving  a  flour  mill,  pretty  close  checks  could  be  made  upon 
the  fuel  consumption.  About  the  only  criticism  that  could 
be  made,  was,  that  at  times,  especially  at  short  cut-off,  the  cut- 


STEAM  PISTONS  283 

off  corner  of  the  diagram  was  rather  too  much  rounded  for 
best  appearances  and  best  results.  A  great  deal  of  adjusting 
of  the  eccentrics,  and  changing  of  the  valve  rods  and  arms, 
were  tried  for  several  weeks,  and  in  fact  for  a  few  months,  but 
although  now  and  then  changing  the  sound,  did  not  make  any 
particular  improvement.  The  top  cylinder  head  was  repeat- 
edly taken  off,  but  invariably  everything  was  found  in  proper 
order.  But  finally  it  was  noticed  that  the  packing  rings,  two 
in  number,  had  considerable  space  back  of  them,  and  depended 
entirely  upon  the  springs  to  hold  them  out;  and  also  that  the 
counterbore  was  unusually  deep  and  long,  in  fact  so  long  that 
the  rings  overtraveled  about  }  of  an  inch.  The  idea  was  then 
suddenly  evolved  that  the  initial  pressure  drove  back  one  of 
the  packing  rings,  as  it  was  so  far  beyond  the  real  cylinder 
bore  at  the  ends  of  the  stroke,  until  the  piston  traveled  a 
few  inches,  and  then  bang!  would  go  the  ring  against  the  bore 
as  it  returned  to  its  proper  place.  Some  chocks  or  lugs  were 
bolted  into  the  bottom  of  the  groove  back  of  the  packing  rings 
so  as  to  project  between  the  springs  and  come  within  about 
3*2  of  an  inch  of  the  back  of  the  rings,  and  this  completely 
cured  the  trouble  both  as  to  noise  and  waste  of  steam. 

In  Fig.  77  the  springs  are  made  as  shown  and  put  into  place 
by  a  slight  compression.  The  entire  construction  of  this  pis- 
ton is  massive,  simple,  and  effective;  the  packing  ring  just 
free  enough  to  adjust  itself  at  all  times  against  the  cylinder, 
under  control  of  the  springs  and  with  only  enough  lateral  move- 
ment  to  insure  its  free  action.  The  load  put  upon  this  pis- 
ton by  the  incoming  steam  at  the  beginning  of  the  stroke  is 
85,000  Ibs.  or  about  43  net  tons;  and  the  weight  of  the  piston 
complete  with  its  rod  is  about  3,000  Ibs. 

Fig.  78  shows  a  56  inch  piston  made  in  general  features  sim- 
ilar to  the  30  inch  just  described,  and  differing  only  as  would 
be  natural  in  the  larger  form.  The  depth  of  this  piston  is  12 
inches,  the  same  as  the  30  inch,  and  is  the  intermediate  piston 
for  the  same  triple  expansion  engines  to  which  the  30  inch 
belongs,  but  would  of  course  answer  for  any  vertical  cylinder 


284 


PUMPING  ENGINES 


of  56  inches  diameter.  The  follower  in  this  case  is  only  a 
ring  with  an  outside  diameter  of  56  inches  and  an  inside  dia- 
meter of  44  inches,  held  in  place  by  12  tap  bolts,  1}  inches 
diameter  and  3  inches  long  under  the  heads.  The  sectional 
view  shows  the  piston  head  to  be  cast  hollow,  with  seats  at 
the  center  for  the  piston  rod  collar  and  nut,  and  with  bearing 
surface  at  the  outer  upper  edge  for  the  follower;  the  right  hand 


Fig.  78. —  Steam  Piston  56  inches  in  Diameter. 

shows  the  bearing  of  the  follower  between  the  bolts,  and  the 
left  hand  the  bearing  at  the  bolt  heads,  and  it  may  be  noted 
how  the  follower  is  cut  away  at  certain  places  so  as  to  make 
it  fit  at  the  necessary  points  and  at  the  same  time  be  easy  to 
remove  and  put  in  place. 

The  packing  ring  in  this  as  in  the  last  piston  mentioned,  is 
very  limited  in  its  movements,  although  perfectly  free  to 
adjust  itself  against  the  cylinder  under  the  influence  of  the 
springs,  which  are  located  in  the  small  space  shown  between 
the  back  of  the  ring  and  the  bottom  of  the  groove.  There 
are  20  steel  springs  in  this  piston,  quite  moderate  in  their 


STEAM  PISTONS 


285 


pressure  against  the  packing  ring,  in  fact  pressing  only  hard 
enough  to  keep  the  sliding  contact  perfect  during  the  strokes 
of  the  piston.  The  plan  view  shows  the  ribs  radiating  from 
the  central  hub  to  the  outer  edge  of  the  piston  head,  for  strength- 
ening and  stiffening  the  construction;  and  also  shows  the  posi- 
tions of  12  plugs  4  inches  in  diameter  where  the  openings  were 
left  in  the  head  by  the  supports  for  the  main  core  when  the 


Fig.  79.— Steam  Piston  84  inches  in  Diameter. 

casting  was  made.  The  necessity  for  the  great  strength 
required  in  a  steam  piston  may  be  understood  when  it  is  real- 
ized that  the  net  load  caused  by  the  steam  pressure  at  the 
beginning  of  the  stroke,  on  this  piston  amounts  to  over  86,000 
Ibs.  or  about  43  net  tons.  This  piston  and  its  rod  weighs 
nearly  5,000  Ibs. 

Fig.  79  shows  an  84  inch  piston  closely  similar  in  construc- 
tion to  the  56  inch  piston  just  described,  and  has  the  same 


286  PUMPING  ENGINES 

depth  of  12  inches;  and  in  fact  is  the  low  pressure  piston  for 
the  same  triple  engine  the  cylinders  of  which  are  30  and  56 
and  84  inches  diameter,  and  of  60  inches  stroke;  but  of  course 
in  a  compound,  or  in  a  straight  low  pressure  condensing  engine, 
the  same  piston  would  answer. 

The  follower  of  this  piston  is  also  a  ring  with  a  diameter 
outside  of  84  inches,  and  a  diameter  inside  of  71  i  inches.  The 
follower  bolts  are  tap  bolts,  12  in  number,  1J  inches  diameter, 
and  3  inches  long  under  the  heads.  The  section  shows  the 
construction  and  the  plan  view  the  location  of  the  stiffening 
ribs,  with  two  rings  of  core  holes,  one  ring  with  three  inch 
and  one  with  four  inch  plugs.  The  construction,  fitting,  and 
bolting  of  the  follower  are  the  same  as  in  the  56  inch  piston, 
and  also  the  general  arrangement  of  the  packing  rings  and 
springs;  but  in  this  large  piston  there  are  30  of  the  steel  springs 
for  holding  out  the  packing.  The  load  upon  this  piston  at 
the  beginning  of  the  stroke  is  about  53,000  Ibs.,  and  the  piston 
and  its  rod  weighs  about  7,500  Ibs. 

These  pistons  are  very  perfectly  made  and  fitted  up,  and 
even  with  the  single  packing  ring  give  every  evidence  of  the 
highest  efficiency  so  far  as  concerns  the  two  principal  require- 
ments, viz.,  working  with  the  least  possible  friction,  and  keep- 
ing the  steam  from  leaking  past  while  the  engine  is  at  work. 
These  particular  pistons  are  in  the  cylinders  of  a  vertical  engine, 
so  that  with  no  weight  bearing  upon  the  interior  surface  of  the 
cylinders,  and  with  such  slight  springs  as  they  have  in  them 
for  holding  out  the  packing,  it  can  readily  be  imagined  how 
easily  and  smoothly  they  must  move  in  doing  their  work. 
Such  pistons  are  sometimes  made  as  large  as  110  inches  in 
diameter  for  low  pressure  cylinders  of  pumping  engines,  and 
from  the  high  economy  of  such  engines,  (they  hold  the  high  duty 
record,)  must  be  all  that  can  be  desired. 

The  foregoing  illustrations,  showing  steam  pistons  from  16 
to  84  inches  diameter,  really  cover  about  all  that  would  be 
necessary  in  producing  pumping  engines,  small  and  large,  hori- 
zontal and  vertical;  and  these  samples  are  taken  from  actual 


STEAM  PISTONS  287 

engines  with  which  the  writer  is  familiar  and  has  had  to  do  in 
ordinary  practice;  such  engines  have  been  built  and  are  run- 
ning in  regular  daily  service  with  perfect  satisfaction.  Of 
course,  different  designers  hold  various  views  about  pistons; 
so  they  do  about  many  other  details ;  but  it  goes  without  saying 
that  simplicity,  strength,  and  effectiveness  are  very  much  to 
be  desired  in  this  class  of  work. 


CHAPTER  XXII 

STEAM  CYLINDERS 

THE  proportions,  design,  construction,  and  arrangement  of 
the  steam  cylinders  of  pumping  engines  have  attracted  and 
received  a  very  large  share  of  the  attention  devoted  to  the 
production  of  such  machinery.  And  deservedly  so.  For  the 
steam  cylinder  is  really  the  heart  of  the  engine,  with  the  strokes 
of  the  piston  representing  the  life  beats  of  the  system.  The 
great  study  has  been  to  get  the  steam  into  and  out  of  the  cylin- 
der with  the  least  amount  of  loss,  and  the  greatest  amount  of  work 
possible  to  derive  from  the  heat  supplied  in  the  form  of  steam. 

Strictly  speaking,  a  proper  cylinder  is  nothing  more  nor  less 
than  a  perfectly  round  barrel  true  to  the  circular  form  and  of 
the  same  diameter  at  all  parts  of  its  length.  But  there  are 
numerous  ways  of  construction,  and  of  securing  the  cylinder 
in  its  place  so  that  the  piston  may  do  its  work  in  the  most 
advantageous  manner,  and  with  the  least  practicable  amount 
of  friction  in  its  movements. 

Before  the  steam  jacket  came  so  generally  into  use,  the  con- 
struction of  a  steam  cylinder  was  a  reasonably  simple  part  of 
the  founder's  and  machinist's  art.  The  steam  jacket  has  been 
known  a  hundred  years  or  more,  but  before  the  idea  had  been 
well  grasped  by  steam  engineers  and  steam  engine  designers 
that  the  heat  was  the  vital  factor,  and  not  the  mere  brute  force 
of  the  steam  pressure  displacing  a  piston,  nearly  if  not  quite 
all  of  the  cylinders  were  made  without  jackets,  the  protection 
of  the  outside  surface  against  outward  radiation  seeming  to  be 
all  that  was  thought  to  be  necessary.  For  very  many  years 
the  steam  pressures  were  low  and  the  internal  expansion  of  the 
steam  within  the  cylinder  was  not  carried  out  to  any  very 

288 


STEAM  CYLINDERS  289 

great  extent.  But  with  high  pressures  and  high  ratios  of  ex- 
pansion, it  can  be  plainly  shown  that  the  entire  question  is  one 
of  heat  expended  in  proportion  to  work  done,  and  that  instead 
of  this  brute  force  pressure  from  the  boiler  to  the  piston,  the 
steam  is  only  the  means  by  which  the  element  we  know  as  heat 
is  carried  from  the  place  of  combustion  in  the  boiler  furnace 
to  the  place  of  being  converted  into  mechanical  energy  or 
work,  within  the  engine  cylinder.  One  of  the  clearest  and 
most  interesting  demonstrations  of  the  real  cause  of  the  power 
of  steam  as  resulting  from  the  use  of  heat,  is  given  by  a  steam 
jacketed  engine  when  its  revolutions  are  increased  or  dimin- 
ished by  manipulating  the  jacket  steam  only,  and  independ- 
ently of  the  steam  going  into  the  cylinder  barrel  where  the 
piston  is  at  work,  the  load,  and  all  conditions  of  admission, 
steam  pressure,  and  cut-off  remaining  the  same.  The  greatest 
economy  in  proportion  to  the  work  done  can  only  be  obtained 
by  a  proper  proportion  between  the  amount  of  steam  admitted 
into  the  cylinder  bore,  and  the  amount  of  steam  admitted  into 
the  jacket  space;  but  the  fact  that  heat  conducted  or  sent 
through  the  cast  iron  walls  of  the  cylinder,  from  the  steam  in 
the  jacket,  will  increase  the  mechanical  work  done  by  the 
engine,  shows  very  clearly  the  real  cause  of  the  energy  indicated 
by  the  engine.  In  other  words,  the  question  is  in  using  steam 
jackets,  how  much  of  the  steam  shall  we  expend  in  the  jackets, 
and  how  much  shall  we  expend  within  the  cylinder  itself  to 
obtain  the  best  results? 

This  question  naturally  enough  leads  to  a  very  serious  and 
studious  consideration  of  the  arrangement  of  the  steam  jacket; 
its  formation  in  practically  making  the  cylinder,  and  the  means 
of  keeping  the  jacket  space  steam  tight,  under  control,  and 
supplying  it  with  steam.  There  is  little  or  no  reason  to  doubt 
that  in  engines  of  fairly  good  size,  say  with  30  inch  high  pres- 
sure cylinders,  and  correspondingly  large  intermediate  and 
low  pressure  cylinders  if  triple,  and  low  pressure  only  if  com- 
pound, the  jacketing  ot  the  cylinder  heads  is  extremely  impor- 
tant, and  in  fact  more  valuable  than  in  jacketing  at  the  sides  of 


290  PUMPING  ENGINES 

the  barrel,  for  reasons  already  explained  in  the  chapter  on  steam 
jacketing.  But  for  all  that,  the  practice  is  generally  to  pay  a 
great  deal  more  attention  to  jacketing  the  sides  and  not  the 
heads,  probably  for  the  reason  that  the  sides  are  easier  to 
jacket;  and  the  question  of  the  real  economy  of  the  steam 
jacket  is  not  as  a  rule  very  thoroughly  looked  into.  It  is  also 
very  important  to  have  steam  jackets  designed  so  as  to  obtain 
effective  circulation  of  the  steam  or  hot  water  as  the  case  may 
be,  and  also  to  have  arrangementr  so  that  the  circulating  may 
be  absolutely  controlled  at  will  so  as  to  adjust  the  work  of 
the  jackets  to  the  best  performance  of  the  engine.  Steam  at 
boiler  pressure  is  generally  admitted  into  the  jacket  of  the 
high  pressure  cylinder  and  the  piping  arranged  accordingly;  but 
it  has  become  evident  that  the  condensation  from  the  high 
pressure  jacket  consisting  partly  of  hot  water  and  partly  steam 
at  a  low  pressure  will  give  the  best  economy  in  the  jackets  fol- 
lowing the  high  pressure;  and  it  is  also  evident  that  when  the 
steam  is  piped  so  as  to  go  into  the  intermediate  and  low  pres- 
sure jackets  at  anything  like  boiler  pressure,  there  will  be  a 
loss  instead  of  a  gain  in  the  total  operation.  As  an  example  of 
an  excellent  plan  of  jacket  pressures  and  connections,  where, 
however,  the  cylinder  heads  were  not  jacketed  aside  from  the 
steam  which  passed  to  and  through  the  valves  situated  in  the 
cylinder  heads,  the  following  may  be  noted: 

Pressure  in  high  pressure  jacket,  151  Ibs.  main  steam  pipe. 

Pressure  in  intermediate  jacket,  40  Ibs. 

Pressure  in  low  pressure  jacket,  0  Ibs.  (Atmosphere.) 
Jacket  pipe  1  \  inches,  from  the  main  steam  pipe  to  the  top  of 
the  barrel  of  the  high  pressure  cylinder,  and  out  at  the  bottom 
of  the  jacket  space.  A  steam  trap  at  the  bottom  of  the  high 
pressure  outlet  pipe  delivers  the  water  of  condensation  to  the 
pipe  leading  to  the  top  of  the  low  pressure  barrel  jacket. 

A  branch  from  the  high  pressure  outlet,  between  the  steam 
trap  above  referred  to  and  the  high  pressure  jacket,  leads  to  the 
top  of  the  coil  in  the  first  receiver,  the  pressure  being  regulated 
to  suit  economy;  the  outlet  from  the  bottom  of  the  first  receiver 


STEAM  CYLINDERS  291 

coil  leads  to  the  top  of  the  intermediate  jacket;  then  from  the 
bottom  of  the  intermediate  jacket  to  the  top  of  the  low  pressure 
jacket;  the  final  outlet  from  the  low  pressure  jacket  leads  to  a 
water  seal  in  the  basement,  the  pressure  being  so  low  that  no 
steam  trap  is  needed  on  the  low  pressure  outlet. 

The  drain  from  the  body  of  the  first  receiver  and  a  small 
portion  of  the  working  steam,  enough  to  ensure  all  of  the  water 
leaving  the  receiver,  is  sent  to  the  top  of  the  coil  of  the  second 
receiver;  and  from  the  bottom  of  the  second  receiver  coil  to  the 
top  of  the  low  pressure  jacket. 

In  coming  to  the  matter  of  actual  construction  and  opera- 
tion, the  factor  of  expansion  of  the  iron  of  which  the  cylinder 
is  made  comes  in  for  a  great  deal  of  attention,  and  it  is  pretty 
safe  to  say  that  in  proportion  to  benefits  derived,  there  is  no 
detail  of  a  steam  engine  which  has  given  so  much  trouble, 
expense,  and  annoyance  as  the  steam  jacket.  There  are  several 
ways  of  forming  the  narrow  annular  or  circular  space  around 
the  steam  cylinder  which  constitutes  the  jacket  space,  but 
perhaps  three  methods  will  cover  the  greater  portion  of  the 
actual  practice  in  this  line. 

First:  The  casting  of  the  jacket  and  the  real  steam  cylinder 
in  one  piece,  by  making  a  steam  cylinder  to  consist  of  two 
shells  separated  from  each  other  by  the  jacket  space,  and  held 
together  and  in  proper  relation  by  means  of  a  series  of  ribs 
which  form  a  part  of  the  casting,  and  permanently  connect  the 
two  shells  together.  In  such  a  plan,  openings  at  the  ends  of 
the  cylinder,  which  are  sometimes  formed  opposite  the  jacket 
space,  necessary  for  the  support  of  the  cores  which  form  the 
jacket  space  itself,  are  either  plugged  after  the  cylinder  is  fin- 
ished, or  left  open,  or  a  portion  of  them  are  left  open,  so  that 
the  side  jackets,  and  the  head  jackets  when  such  are  used,  may 
have  free  circulation  of  steam.  Sometimes,  where  the  cylinder 
heads  are  let  several  inches  into  the  ends  of  the  cylinder,  so 
as  to  fill  up  the  space  between  the  steam  ports  and  the  cylinder 
ends,  the  barrel  and  head  jackets  are  entirely  separated  by 
the  position  of  the  cores,  and  the  circulation  of  steam  is  accom- 


292 


PUMPING  ENGINES 


Fig.  80.  — Section  of  Steam 
Jacket  cast  on  the  Cylinder. 


Fig.  81. — Section  of  Steam  Jacket 
cast  on  the  Cylinder. 


plished  by  means  of  properly  connected  pipes  outside  of  the 
cylinder  and  heads.  Fig.  80  and  Fig.  81 
show  sections  lengthwise  of  the  steam 
cylinder  with  a  steam  jacket  cast  on; 
and  also  a  cross  section  showing  the  cir- 
cular space  between  the  inner  and  outer 
shells  of  the  cylinder.  In  these  figures 
both  the  sides  of  the  barrel  and  the 
cylinder  heads  are  steam  jacketed. 

Second:  The  making  of  the  main  shell 
of  the  cylinder  containing  the  valve 
seats  at  each  end,  as  a  separate  casting, 
and  the  inserting  within  this  main  cyl- 
inder casting  an  inner  shell  which  forms 
the  real  cylinder  in  which  the  piston 
works.  The  inner  cylinder  only  is 
bored,  but  there  are  bearings  or  fitting 
places  at  each  end  of  the  main  casting 
for  securing  steam  tight  the  ends  of  the  Fig.  82.— Eeynoids  steam  Jacket 

two   Shells  together,  and  thus  forming  ™de  Separate  from  the  Cylinder. 

the  regular  circular  space  for  the  steam  jacket.     (See  Fig.  82.) 
The  cylinder  heads  in  this  form  of  construction  are  some- 


STEAM    CYLINDERS 


293 


times  jacketed  and  sometimes  not;  and  the  general  arrange- 
ments of  connecting  the  circulation  of  the  jacket  steam  are 
similar  to  those  for  the  jackets  shown  in  Fig.  80  and  Fig. 
81.  In  the  form  of  jacket  construction  shown  in  Fig.  82,  the 
cylinder  when  planned  for  having  its  valves  across  the  cylinder 
heads,  as  is  found  in  important  and  large  engines,  is  simply  a 
plain  flanged  barrel  of  cast  iron,  fitted  with  an  internal  barrel 
for  forming  the  circular  space;  both  of  these  barrels  finished 


Fig.  83.  —  Bottom  Cylinder  Head  with 
Reynolds  Steam  Jacket. 


Fig.  84.  — Enlarged  Section  of  Upper 
End  of  Cylinder  and  Jacket. 


flush  at  one  end  with  a  flange  common  to  both  for  bolting  on 
the  cylinder  head  at  that  end,  usually  the  free  or  outer  or 
upper  end  of  the  cylinder.  The  end  of  the  cylinder  next  to  the 
engine  frame,  or  what  might  be  called  the  inner  or  lower  end 
of  the  cylinder,  is  arranged  slightly  different  from  the  other 
end;  the  main,  or  inner,  or  working  cylinder,  is  formed  with 
a  flange  which  is  arranged  for  bolting  to  the  bottom  cylinder 
head,  and  then  the  outer  or  jacket  shell  has  a  flange  which  is 
fitted  on  top  of  the  flange  of  the  working  cylinder,  one  set  of 
studs  secured  in  the  cylinder  head  passing  through  both  flanges 
as  shown  in  Fig.  83.  Fig.  84  shows  an  enlarged  section  of  the 
upper  or  outer  end  of  the  working  and  jacket  shells. 


294 


PUMPING  ENGINES 


In  this  form  of  construction,  which  is  the  most  favored  for 
both  small  and  large  engines  of  the  better  class,  all  of  the  steam 
and  exhaust  ports,  valve  chambers  and  seats,  steam  chests, 


Fig.  85.  — Section  of  Cylinder  with  Corliss  Valves. 

etc.,  are  contained  within  the  cylinder  heads.     (See  Fig.  85  for 
sectional  views  of  such  cylinder  heads,  fitted  with  Corliss  valves.) 


Fig.  86.— Section  of  Steam  Cylinder  with  Side  Pipes. 

Fig.  88  shows  a  complete  section  of  this  type  of  steam  cylin- 


STEAM    CYLINDERS 


295 


der  with  side  pipes  for  steam  and  exhaust  arranged  with  expan- 
sion joints,  to  compensate  or  allow  for  unequal  expansion  and 
contraction  which  is  bound  to  be  present  in  any  construction 
employing  several  different  pieces  of  metal  fastened  at  their 
ends  to  the  same  terminal  members,  and  where  it  is  absolutely 
necessary  to  maintain  steam  tight  joints. 
In  this  form  of  cylinder  the  working  and  jacket  shells  are 


Fig,  87.  —  Cylinder  Section  with  Bibs  and  Pipe  Nozzles. 

really  formed  into  one  complete  barrel,  expanding  and  con- 
tracting alike;  but  the  steam  and  exhaust  pipes  are  not  only 
at  different  temperatures  and  pressures  from  the  cylinders, 
but  also  different  from  each  other.  Hence,  the  rather  com- 
plicated, but  extremely  efficient,  scheme  of  construction. 

Fig.  87  shows  a  section  through  the  steam  chest  at  the  cen- 
ter line  of  the  valve  circle,  and  indicates  the  ribs  for  strength- 
ening the  flat  surfaces,  also  showing  the  location  of  the  steam 
and  exhaust  side  pipes  which  distribute  the  incoming  steam 
to  both  ends  of  the  cylinder  and  take  away  the  exhaust;  the 
extreme  outer  flanged  nozzle  showing  where  the  connections 
are  made  to  the  main  steam  pipe,  a  receiver  steam  pipe,  or 
exhaust  pipe,  or  a  pipe  to  the  condenser,  according  to  the 
class  and  character  of  the  cylinder  or  engine  to  which  it  belongs. 


296 


PUMPING  ENGINES 


Where  poppet  valves  are  used  for  the  low  pressure  cylinder 
of  a  triple  expansion  pumping  engine,  for  the  purpose  of  re- 
ducing the  clearance  or  waste  room  at  the  cylinder  ends  to  the 
lowest  possible  amount,  the  general  construction  of  the  cylin- 
der and  cylinder  head  is  the  same  as  already  described,  but 
of  course  the  steam  chest  is  very  different  from  that  of  the 
Corliss  type  of  valve.  The  idea  of  poppet  valves  is  to  have 
them  close  flush  or  even  with  the  inside  surface  of  the  cylinder 
head  so  that  when  the  steam  and  exhaust  valves  are  closed, 
there  will  be  no  waste  room  on  account  of  steam  ports,  as  the 


Fig.  88.  — Poppet  Valves  Closed. 


Fig.  89. 


t    f 

Steam  and  Exhaust  Valves  off  the  Seats. 


only  port  is  the  circular  opening  left  by  the  poppet  valve  when 
it  leaves  its  seat.  There  is  the  clearance  between  the  piston 
and  the  cylinder  head,  but  this  is  brought  down  to  a  very  small 
amount,  and  is  in  fact  about  all  the  loss  of  steam  there  is.  The 
general  idea  may  be  understood  by  means  of  Fig.  88  and  Fig. 
89,  the  former  showing  in  a  simple  way  the  position  of  the 
poppet  valves  when  closed,  and  the  latter  showing  a  steam 
and  exhaust  valve  off  their  seats;  the  steam  valve  opening 


STEAM  CYLINDERS 


297 


away  from  the  interior  of  the  cylinder,  and  the  exhaust  valve 
opening  into  the  cylinder,  it  being  remembered  that  the  ex- 
haust valve  opens  when  the  piston  is  at  the  opposite  end  of 
the  cylinder  fiom  the  particular  valve  opening,  and  will  close 
before  the  piston  reaches  it  on  the  return  stroke ;  it  will  also  be 
observed  that  even  if  the  exhaust  valve  stem  should  stick 
in  the  packing  or  anything  else  hang  the  valve  open,  the  pis- 


Fig.  90.  —  Ports  of  Corliss  Valves  Across  the  Heads. 

ton  will  push  it  shut  without  doing  any  damage.  The  steam 
valve  opens  away  from  the  cylinder  and  will  never  interfere 
with  the  piston. 

With  the  Corliss  type,  even  when  the  valves    are    placed 
across  the  cylinder  head,  the   ports  which    carry  the    steam 


Fig.  91.  —  Forts  of  Corliss  Valves  Across  the  Heads. 

through  the  head  into  and  out  of  the  cylinder  represent  waste 
space  that  must  be  filled  with  steam  at  each  stroke  of  the  pis- 
ton. Fig.  90  and  Fig.  91  illustrate  these  points,  and  the 


298  PUMPING  ENGINES 

ports  show  lost  spaces  which  do  not  exist  at  all  with  the  pop- 
pet form  of  valve.  In  high  pressure  or  intermediate  cylinders, 
this  extremely  fine  point  of  clearness  does  not  matter  so  much 
because  the  steam  is  used  again  in  the  low  pressure  cylinder; 
but  the  latter  cylinder  sends  its  steam  to  the  condenser,  and 
all  waste  space  filled  in  this  cylinder  represents  a  certain  loss 
which  cannot  be  made  good. 

Twenty  years  ago,  from  3  to  5  per  cent  of  the  cylinder  vol- 
ume did  not  apparently  attract  very  much  attention  or  adverse 
criticism  as  waste  room,  but  in  the  light  of  experience  the  waste 
room  has  been  gradually  reduced  by  different  arrangements  of 
steam  valves  and  ports  until  now  the  extreme  refinement  in 
this  direction  has  brought  the  waste  room  down  to  1-J  per  cent 
in  high  pressure  cylinders,  and  0.8  per  cent  in  low  pressure 
cylinders  in  compound  engines;  and  to  1|  per  cent  in  high  press- 
ure, 0.75  per  cent  in  intermediate,  and  OJ  per  cent  in  low  press- 
ure cylinders  of  triple  expansion  engines.  There  is  no  special 
reason  why  the  compounds  are  not  calculated  as  closely  as  the 
triples,  beyond  the  apparent  idea  that  the  compounds  are  not 
regarded  as  of  so  much  importance  as  the  triples,  and  are  to 
a  certain  extent  tolerated  under  special  conditions  where  for 
some  reasons  it  is  not  considered  necessary  or  desirable  to  go 
to  the  refinements  or  cost  of  the  triple  machine. 

The  cylinder  head  joints  and  the  piston  rod  packing  has 
been  gradually  improved  and  brought  to  a  great  degree  of 
perfection  in  these  latter  days  of  construction  in  the  endeavor 
to  reduce  leakages  and  repairs  to  the  lowest  terms;  and  prob- 
ably the  desire  to  excel  by  builders  of  pumping  engines  for 
municipal  water  works,  has  been  the  greatest  incentive  to 
better  and  better  work.  Mill  engines  and  electric  railroad 
engines  do  not  seem  to  offer  the  inducement  to  excel,  prob- 
ably because  their  performance  cannot,  in  the  nature  of  their 
load,  be  so  minutely  determined  as  in  the  case  of  pumping 
machinery,  where  the  load  can  be  brought  to  a  constant  quan- 
tity for  any  reasonable  length  of  time  for  testing  purposes. 

The  lower  heads  of  vertical  cylinders,  and  the  inner  heads  of 


UNIVERSITY 

OF 


STEAM    ENGINES 


299 


horizontal  cylinders,  are  strongly  ribbed  and  made  in  special 
forms  where  they  are  bolted  to  the  engine  framing,  this  portion 
of  the  work  of  course  being  very  important  as  the  entire  thrust 
and  energy  of  the  machine  is  alternately  pushing  and  pulling 
upon  the  place  of  connection,  constantly  changing  in  intensity 
and  degree  as  the  pressure  changes  from  initial  to  terminal. 
The  clothing  or  covering  of  the  steam  cylinders  to  protect 
them  from  the  loss  of  heat  radiating  from  their  outer  surfaces, 
has  long  been  recognized  as  a  vital  matter,  and  nowadays  has 
been  brought  to  a  systematic  and  effective  point.  Probably 
one  of  the  very  best  methods  is  to  apply  a  plastic  covering  of 
some  asbestos  or  magnesia  mixture  directly  upon  the  heated 
iron,  to  a  thickness  of  about  1J 
inches,  and  then  outside  of  this 
place  two  thicknesses  of  f  inch  hair 
felt.  Outside  of  this  comes  the 
lagging  or  ornamental  covering  of 
steel  or  wood,  partly  for  appear- 
ances and  partly  for  the  protection 
of  the  non-conducting  material. 

Third :  The  making  of  the  inner 
or  working  cylinder  in  which  the 
piston  operates  in  one  complete 
barrel,  but  with  the  outer  shell 
which  forms  the  steam  jacket  in 
two  parts.  These  two  parts  of  the 
outer  shell  are  cast  solid  with  the 
working  cylinder  at  each  end  of 
the  latter,  but  terminate  a  little 
short  at  the  middle  of  the  length 
of  the  cylinder  so  as  to  leave  a  gap 
in  the  jacket  cylinder  with  the 
edges  free.  The  opening  so  formed  Flg' 
is  closed  steam  tight  by  a  copper 
expansion  joint,  the  result  being  that  as  the  inner  or  working 
cylinder  expands  and  contracts  by  heat  or  the  lack  of  heat,  the 


•• 

Designed  by  E.  D.  Leavitt. 


300  PUMPING  ENGINES 

jacket  cylinder  can  accommodate  itself  on  account  of  the  curved 
copper  joint  shown.  (See  Fig.  92  for  the  general  section  of  the 
cylinder  showing  the  working  barrel  and  the  jacket  barrel ;  also 
see  Fig.  93  for  an  enlarged  section  of  a  portion  of  the  copper 
joint  and  ends  of  the  jacket  barrel.)  This  corrugated  copper 
band  forming  the  expansion  element  for  the  joint  is  secured 
in  place  with  great  care,  by  using  two  rows  of  comparatively 
large  tap  bolts  at  each  side  of  the  barrel  opening;  it  is  bolted 


Fig.  93.  — Enlarged  Section  of  Leavitt  Steam  Jacket. 

very  firmly  down,  metal  to  metal,  and  caulked  at  the  edges; 
the  copper  band  being  spun- from  a  complete  piece  of  metal 
and  with  no  joint  in  itself.  This  expansion  joint  for  a  steam 
jacket  has  been  found  to  give  good  satisfaction  and  is  both 
scientifically  and  practically  correct  in  its  idea. 

In  this  particular  form  of  steam  cylinder  the  valve  or  steam 
chests  are  located  across  each  end  at  the  side  of  the  cylinder,  and 
are  arranged  for  flat  gridiron  slide  Valves,  the  valve  seats  being 
independent  and  bolted  in  place.  Many  attempts  have  been 
made  and  much  money  spent  in  machining,  fitting,  and  scrap- 
ing such  valves  to  make  them  absolutely  steam  tight-  under 
working  conditions,  in  some  cases  the  work  being  finished 
with  the  cylinders  hot  so  as  to  meet  any  distortions  which  may 
come  from  unequal  expansion  of  the  metal.  Many  cases  have 
been  observed  in  connection  with  certain  details  of  steam  machin- 
ery, in  which  the  metal  did  not  maintain  the  same  form  after 
being  heated  as  it  had  when  it  was  cold,  especially  where  flat 
surfaces  were  being  dealt  with;  such  as  these  valves  and  their 


'STEAM  CYLINDERS  301 

seats  have.  The  skill  and  quality  of  the  work  sometimes  put 
upon  these  flat  gridiron  valves  and  seats  no  doubt  represent 
the  highest  art  of  the  machinist,  and  the  valves  are  made 
perfectly  tight  under  steam  and  apparently  remain  so  for  years. 

But  be  this  as  it  may,  the  record  for  the  highest  steam  econ- 
omy is  not  held  -by  engines  fitted  with  this  flat  sort  of  valve, 
but  with  a  combination  of  Corliss  and  poppet  valves,  and  with- 
out such  refinements  and  expensive  niceties  of  workmanship 
as  is  often  devoted  to  the  gridiron  slide.  The  only  reason 
possible  to  apply  to  such  a  state  of  things,  is  that  with  the 
absolutely  steam  tight  slide  valves  there  goes  an  abnormally 
large  amount  of  clearance  or  waste  room  on  account  of  the 
position  in  which  it  is  necessary  to  place  such  valves  so  as  to 
provide  enough  inlet  and  outlet  for  the  steam.  All  engines 
must  have  some  clearness  between  the  piston  and  the  cylin- 
der head,  but  the  poppet  valve  wipes  out  of  existence  all  other 
foims  of  waste  room,  and  no  other  form  of  steam  valve  does. 
The  low  pressure  cylinder  being  the  last  cylinder,  between  the 
boiler  and  the  condenser,  under  its  very  moderate  pressure 
it  is  possible  to  operate  large  poppet  valves  and  their  mechan- 
ism; these  valves  also  being  quite  easy  to  grind  to  a  steam 
tight  fit  upon  their  seats.  A  pumping  engine  being  so  pro- 
vided with  such  valves  at  the  final  outlet  can  afford  to  use 
valves  in  the  other  cylinders  which  perhaps  may  not  be  as 
perfectly  steam  tight  as  some  other  forms,  although  the  Cor- 
liss valve  properly  proportioned  and  fitted  comes  pretty  near, 
to  say  the  least,  to  being  a  steam  tight  member,  and  coupled 
with  this  is  the  fact  of  its  very  low  amount  of  waste  room 
when  placed  across  the  cylinder  head. 

With  this  third  form  of  jacket  application  in  making  the 
cylinder  casting,  any  and  all  of  the  forms  of  valves,  side  pipes, 
and  steam  connections  may  be  used,  that  are  employed  with 
either  of  the  other  forms  mentioned  above,  although  for  an 
acceptable  piece  of  work  the  second  arrangement  and  con- 
struction would  be  the  least  costly.  The  matter  of  covering 
and  lagging  would  vary  only  according  to  the  construction 


302  PUMPING  ENGINES 

and   arrangement  of   detail  of   the  different  forms   of   steam 
cylindeis. 

The  quality  of  the  cast  iron  and  the  accuracy  of  the  boring, 
are  factors  in  the  construction  of  steam  cylinders  not  easy  to 
overestimate,  and  very  likely  do  not  receive  the  careful  atten- 
tion which  their  importance  deserve.  Cylinders  should  be 
made  of  strong  close-grained  tough  iron,  rather  hard;  in  fact, 
if  not  brittle,  just  about  as  hard  as  they  can  be  conveniently 
bored,  and  if  they  could  be  chilled  and  finished  by  grinding, 
so  much  the  better,  although  if  such  work  cannot  be  done 
and  managed  so  as  to  be  reasonably  low  in  cost  it  might  not 
pay.  At  all  events,  the  actual  work  upon  the  cylinder  bore 
is  such  a  small  percentage  of  the  total  work  upon  the  engine, 
that  it  will  pay  to  give  it  some  special  attention  when  the 
life  and  economy  of  the  engine  is  considered,  and  when  it  is 
also  considered  what  it  means  in  the  way  of  work  and  expense, 
stoppage,  and  annoyance,  if  it  should  become  necessary  to 
rebore  the  cylinders  of  an  engine.  In  the  construction  of 
pumping  engines,  where  high  efficiency  is  looked  for  and  where 
consequently  the  clearance  of  the  pistons  at  the  ends  of  the 
stroke  must  be  closely  figured,  .the  boiing  of  the  steam  cylin- 
ders becomes  almost  a  fine  art.  The  inside  of  the  cylinder 
heads  must  be  faced  off  to  a  true  and  smooth  surface;  the  pis- 
ton must  be  finished  to  an  accurate  thickness  and  accurately 
turned  and  faced  so  that  the  distance  between  the  faces  of  the 
cylinder  heads,  will  be  equal  to  the  length  of  the  stroke  of 
the  engine  plus  the  thickness  of  the  piston  and  twice  the 
desired  clearance;  and  this  clearance  in  quite  large  cylin- 
ders is  sometimes  brought  down  to  J  of  an  inch  at  each 
end  of  the  cylinder.  The  counterbore  is  a  detail  of  cylinder 
boring  not  always  appreciated,  and  to  be  correct  should 
be  carried  to  a  point  that  will  allow  the  packing  to  just  nicely 
ride  over  the  ends  of  the  real  bore,  not  more  than  -J  of  an  inch, 
and  closer  than  this  even  down  to  TV  of  an  inch  is  some- 
times figured  and  carried  out  in  this  portion  of  the  work;  in 
fact  plans  are  sometimes  drawn  as  fine  as  •£$  of  an  inch  for 


STEAM  CYLINDERS  303 

the  overrun  of  the  counter  bore  by  the  packing  ring  at  each 
end  of  the  cylinder,  but  it  is  very  doubtful  if  such  fine  calcu- 
lations can  be  carried  out  by  even  the  most  skilled  workmen, 
when  the  making  of  joints  and  the  changing  of  temperatures 
are  considered.  By  an  adjustment  for  length  of  the  piston 
rod  where  it  is  secured  in  the  cross  head,  the  actual  cleai  anco 
between  the  piston  and  the  cylinder  heads  may  be  brought 
down  to  a  very  fine  point,  and  evenly  divided,  with  temper  a- 
ture  allowed  for,  by  skillful  men;  but  to  have  the  overrun 
at  the  counterbores  any  ceitain  amount  and  equally  divided, 
at  the  same  time,  is  calling  for  work  almost  if  not  quite  out- 
side of  human  accomplishment.  The  object  of  the  counter- 
bore  is  to  allow  the  packing  of  the  piston,  that  is,  the  ring  or 
rings,  to  clear  the  ends  of  the  real  bore  at  each  stroke  and  so 
avoid  wearing  shoulders  in  the  cylinder  surface,  which  would 
make  themselves  felt  and  heard  when  the  length  of  the  con- 
nections happened  to  be  changed  by  taking  up  lost  motion 
from  time  to  time. 


CHAPTER   XXIII 

CROSS  HEADS 

ONE  of  the  details  of  a  steam  engine,  and  especially  of  a 
pumping  engine,  that  is  not  very  much  noticed  or  apparently 
thought  of,  is  the  cross  head.  But,  as  it  is  the  connecting  point 
between  the  working  parts  of  the  steam  and  water  ends,  it  is 
really  a  most  important  detail  in  the  operation  of  the  machine. 
In  horizontal,  low  duty,  direct  acting  water  works  pumping 
engines,  that  is,  non-rotative  engines  of  the  Worthington 
type,  the  cross  head  acts  only  as  a  medium  for  connecting  the 
ends  of  one,  two,  or  three  piston  rods,  as  the  case  may  be,  to 
one  plunger  rod;  one  cross  head  and  one  set  of  rods  at  each  side 
of  the  engine.  In  the  regular  machine  as  built  on  the  original 
lines  there  was  one  high  pressure  piston  rod,  extending  towards 
the  water  cylinder  and  entering  the  cross  head  where  it  was 
secured  with  a  substant!al  key.  Then,  back  of  the  high  pres- 
sure piston  the  rod  extended  through  a  sleeve  situated  in  a  head 
between  and  common  to  the  high  and  low  pressure  cylinders, 
into  the  low  pressure  cylinder  and  was  secured  to  the  low  pres- 
sure piston. 

The  plunger  rod  was  keyed  into  the  cross  head  and  extended 
toward  and  into  the  water  cylinder  where  it  was  secured  to 
the  plunger  by  a  nut  or  key  according  to  the  construction  and 
size  of  the  plunger.  Later,  the  heads  between  the  high  and  low 
pressure  cylinders  were  made  solid,  and  there  were  two  low 
pressure  piston  rods  for  each  low  pressure  cylinder,  and,  extend- 
ing from  the  low  pressure  pistons  through  sleeves  alongside 
of  the  high  pressure  cylinders,  were  carried  towards  the  water 
ends  and  secured,  generally  by  nuts,  one  for  each  rod,  to  oppo- 
site ends  of  forged  wrought  iron  or  steel  cross  heads  extending 

304 


CROSS  HEADS  305 

crosswise  of  the  machine.  In  some  makes  of  this  type  of  pump- 
ing engine  the  cross  heads  were  made  of  steel  castings  instead 
of  the  forgings,  the  principle  of  use  being  the  same  and  the 
principal  difference  really  being  in  the  finish,  as  the  forgings 
were  generally  finished  and  polished  all  over,  while  the  steel 
castings  were  only  finished  at  high  paits.  The  plunger  lods 
were  connected  the  same  as  in  the  single  cross  heads  already 
described. 

In  both  of  these  forms  of  cross  heads,  the  weight  and  that 
of  the  rods  was  carried  upon  the  guide  bars  by  means  of  a  brass 
shoe  attached  to  the  under  side  of  the  cross  head.  The  valve 
motion  for  the  steam  cylinders,  and  the  air  pump  beams  were 
driven  from  these  cross  heads,  and  the  entire  design  was  very 
substantial,  neat,  and  effective.  When  the  high  duty  Worth- 
ington  pumping  engine  made  its  appearance  and  was  reduced 
to  a  regular  and  commercial  form,  the  general  plan  was  retained, 
and  the  cross  heads  in  addition  to  their  other  duties,  carried  the 
bearings  for  the  compensating  plunger  heads,  but  the  guides 
were  very  materially  changed,  and  instead  of  a  comparatively 
light  girder  casting  located  just  below  the  center  of  the 
machine,  the  guides  were  formed  within  the  massive  cast  iron 
frames  which  replaced  the  polished  wrought  iron  distance  bars, 
used  in  the  older  machines,  as  framing  between  the  steam  and 
water  ends.  Fig.  94  and  Fig.  95  show  these  cross  heads,  of  the 
original  and  the  later  forms  of  the  non-rotative  pumping  engine. 


i 

Fig.  94, — Cross  Head  of  Early  Worthington  Engine. 

In  the  first  form  of  the  Gaskill  pumping  engine,  built  by  the 
Holly  Manufacturing  Company,  the  cross  heads  were  of  the 
locomotive  type,  sliding  upon  square  bars,  these  bars  also 


306 


PUMPING  ENGINES 


assisting  in  stiffening  and  holding  the  machine  together.  The 
sliding  portion  holding  the  adjustable  shoes  was  located  above 
the  jaw  containing  the  cross  head  pin  for  the  high  pressure 


_~ZZ1_ 


Fig    95.  -  Later  Worthington  Cross  Heads. 

link  journal;  and  below  the  wrist  pin  for  the  low  pressure  cross 
head;  thus  leaving  the  ends  of  the  connecting  rods  and  links 
free,  clear,  and  very  accessible.  In  the  later  engines  of  this 
type  the  open  framework,  somewhat  similar  to  that  of  its  non- 
rotative  rival,  which  marks  the  earlier  machines,  gave  way  to 
cast  iron  girder  frames  in  which  the  guides  were  formed;  and 
the  cross  heads  then  took  on  a  different  form  from  the  originals 
to  conform  to  the  changes  in  the  framing.  In  these  later  cross 
heads,  sliding  blocks  in  each  frame  supported  forged  cross 
pins  which  were  simply  prolongations  of  the  regular  cross  head 
pins.  With  the  later  cross  heads,  the  main  connecting  rods 
were  lengthened  so  that  instead  of  working  upon  pins  at  the 
tops  of  the  vertical  rocking  beams,  they  worked  upon  the  pins 
secured  in  the  cross  head,  above  described.  This  change  gave 
a  longer  connecting  rod  without  lengthening  the  engine,  but 
changed  the  motion  so  that  the  compression  in  the  steam 


CROSS  HEADS 


307 


cylinder  at  the  closing  of  the  exhaust  valve,  and  at  the  moment 
the  engine  passed  the  centers,  was  less  effective  for  smooth 
running. 

Fig.  96  shows  the  early  and  Fig.  97  the  later  cross  head  of 
this  type  of  machine.  In  the  older  type  the  high  pressure  cross 
head  was  keyed  to  the  piston  rod,  and  provided  a  wrist  pin 


Fig.  96.  —  Early  Gaskill  Cross  Heads,  High  and  Low  Pressure. 

for  the  link  which  carried  the  power  to  the  top  end  of  the  rock- 
ing beam,  and  so  the  high  pressure  cylinder  had  no  direct  drive 
upon  the  water  plunger,  but  its  power  was  partly  transmitted 
to  the  fly  wheel  through  the  connecting  rod  which  coupled  to 
the  top  end  of  the  beam  also,  by  a  forked  end;  and  partly  to 
the  lower  link  which  carried  the  power  from  the  rocking  beam 
to  the  plunger  rod.  The  low  pressure  cross  head  was  formed 
so  as  to  receive  two  piston  rods  from  the  low  pressure  cylinder, 
and  between  the  hubs  into  which  these  rods  were  secured, 


308 


PUMPING  ENGINES 


there  was  located  the  wrist  pin  for  connecting  the  lower  beam 
link  already  mentioned;  the  drive  from  the  low  pressure  piston 


Fig.  97.  — Later  Gaskill  Cross  Heads. 

was  directly  to  the  plunger  as  the  plunger  rod  was  keyed  into 
this  cross  head. 

In  the  later  engines,  the  high  pressure  piston  was  keyed  to 
the  cross  head  as  before,  but  the  guide  bar  just  above  the  cross 
head  was  omitted,  and  the  guides  were  formed  in  the  cast  iron 
side  frames  which  took  the  place  of  the  round  bars;  a  jaw  was 
formed  in  the  cross  head  which  took  the  end  of  the  connecting 
rod  instead  of  the  link,  and  the  link  connection  to  the  rocking 
beam  was  made  by  two  links  one  at  each  side  of  the  cross  head 
connecting  with  journals  at  the  outside  of  the  beam;  this  did 
away  with  the  fork  ended  connecting  rod,  but  made  two  links 
necessary. 

In  the  horizontal,  cross  compound  pumping  engines,  which 
have  now  attained  the  dignity  of  a  pronounced  type,  as 
brought  out  by  the  Allis-Chalmers,  the  Platt  Iron 'Works, 
end  Snow  Companies,  the  cross  heads  are  quite  different  from 
those  already  described.  In  these  cross  compounds,  the  cross 
heads  are  formed  with  jaws  for  taking  the  connecting  rod,  and 
travel  on  guides  in  the  lower  part  of  the  frame  in  the  first 
and  last  mentioned  engines,  liberal  hubs  being  provided  for 
securing  distance  rods  which  extend  past  the  crank  shaft  and 


CROSS  HEADS 


309 


into  corresponding  hubs  in  the  plunger  cross  head,  these 
distance  rods  being  placed  diagonally  with  reference  to  the 
cross  section  of  the  engine,  one  rod  above  the  shaft  and  back 
of  the  crank,  and  the  other  rod  in  front  of  the  crank  below  the 
center  line,  thus  forming  a  rigid  drive  from  the  steam  pistons 


HUMP  END  CROSSHEAO  ^-^  MAIN  CROSSHEAD 

Fig.  98. — Cross  Heads  of  Cross  Compound  Pumping  Engines. 

to  the  water  plungers  directly  through  the  cross  head.  This 
makes  one  of  the  most  direct  acting  crank  engines  possible  to 
devise,  as  the  surplus  work  of  the  initial  steam  is  sent  straight 
into  the  fly  wheel,  so  to  speak,  and  when  the  wheel  gives  back 
the  work  in  equalizing  the  expansion  of  the  steam,  the  con- 
necting rod  sends  it  straight  to  the  cross  head  and  so  into  the 
plunger. 

Fig.  98  shows  the  general  construction  of  the  cross  head 
of  the  cross  compound  horizontal  pumping  engine. 

In  vertical  pumping  engines,  the  conditions  and  applica- 
tions of  the  power  to  the  work  of  pumping  are  considerably 
changed  from  those  of  the  horizontal  machine ;  although  the  idea 
of  transmitting  so  far  as  possible  the  work  of  the  steam  pistons 
directly  to  the  water  plungers  is  carried  out  rather  better  in 
the  vertical  machines.  The  Worthington  type  is  for  the  most 
part,  the  horizontal  machine  stood  upon  end  and  the  moving 
parts  balanced  against  gravity  by  means  of  air  pressure  within 
what  is  called  the  balancing  cylinders;  there  being  no  cranks 
and  connecting  rods  attached  to  the  cross  head,  of  course  the 
advantage  cannot  be  taken  of  balancing  one  side  of  the  mechan- 
ism against  the  other,  as  would  be  possible  with  a  vertical 


310 


PUMPING  ENGINES 


cross   compound  engine   having  cranks   opposite   each   other, 
or  with  a  triple  expansion  having  cranks  120  degrees  apart. 

The  Worthington  vertical  engine  has  been  built  mostly 
of  the  high  duty  class,  and  the  cross  heads  besides  forming 
the  usual  medium  for  joining  the  steam  pistons  and  the  water 
plunger  rods,  carry  the  bearings  for  the  journals  of  the  com- 
pensator plungers;  the  cross  heads  being  guided  at  each  end 


1 

H 
3 

TO 

E 
1 

—  .  — 

til 

i 

T|    j    i 

i 

f       '.....I 

i 

f 

i 

Pig.  99.  —  Worthington  Vertical  High  Duty  Cross  Head. 

by  special  guide  castings  secured  to  the  franing  belorv*  the 
bottom  heads  of  the  low  pressure  cylinders;  the  main  framing 
being  entirely  independent  of  the  guides.  From  the  outer  ends 
of  each  cross  head  there  are  driven  the  various  side  rods  whLh 
give  motion  to  the  steam  valve  gear,  each  cross  head  operat- 
ing the  main  valve  motion  for  the  opposite  set  of  cylinders,  and 
the  cut-off  mechanism  for  its  own  set  of  cylinders.  This  cross 
head  is  shown  in  Fig.  99. 

In  the  vertical,  triple  expansion,  and  cross  compound,  crank 
and  fly  wheel  pumping  engines,  at  first,  fifteen  or  twenty  yeais 
ago,  forged  iron  and  steel  cross  heads  were  used,  but  of  late 
years  steel  castings  have  been  introduced,  and  as  the  latter 


CROSS  HEADS 


311 


are  the  less  costly  to  fit  up,  with  the  present  day  facilities  for 
getting  good  annealed  steel  castings,  they  will  probably  hold 
the  preference  in  the  absence  of  some  special  reasons  or  deshe 
for  the  forgings. 

Although  the  more  costly,  the  forged  cross  heads  for  the 
vertical  engines  have  many  attractions  in  design,  accessibility, 
and  appearance.  The  center  of  the  connecting  rod  bearing 
or  wrist  pin  and  the  trunnions  for  receiving  the  guide  shoes, 
come  so  naturally  and  conveniently  in  line  that  they  can  be 
turned  on  the  same  centers,  thus  insuring  absolute  sameness 


Fig.  100.  —  Forged  Steel  Cross  Head  for  Vertical  Triple  Engine. 

of  center  lines  so  desirable  in  cross  heads.  Also,  the  natural 
design  for  a  forging  lends  itself  completely  to  the  accommoda- 
tion of  the  distance  rods  extending  from  the  cross  head  to  the 
plunger  head  below;  also  giving  a  very  convenient  plac3 
for  attaching  either  two  piston  rods,  or  a  b~  idge  tree  for  a  single 
piston.  And  withal  we  have  the  comfortable  consciousness 
that  the  cross  head  is  a  forging  fiom  the  steam  hammer  with 


312 


PUMPING  ENGINES 


all  of  its  parts  and  material  thoroughly  condensed,  known, 
and  in  sight  during  construction  and  operation.  The  forged 
cross  head  had  its  advent  with  the  double  "A"  frame  in  ver- 
tical pumping  engines;  but  since  the  introduction  of  the  single 
"A"  frame,  and  the  tower  form  of  frame,  the  guides  are  so 
formed  and  placed  that  the  original  type  of  forging  does  not 
fit  into  the  construction  so  well.  And,  as  the  single  frame, 
and  the  single  piston  rod  which  so  naturally  accompanies  the 
single  frame,  can  be  made  more  economically  than  the  double 
design,  the  ever  present  evolution  which  brings  the  lowest 
cost  for  an  equally  reliable  result  is  bound  to  hold  sway.  There 
is  no  room  for  doubting  the  superiority  of  the  single  (:  A"  frame, 
for  its  strength,  its  appearance,  and  its  economical  production 
in  the  foundry  and  shop. 
With  the  single  "A"  frame  and  its  internal  guides  there 


Fig.  101. — Cast  Steel  Cross  Head  for  Vertical  Triple  Engine. 

comes  rationally  enough  an  entirely  different  form  of  cross 
head,  a  form  difficult  and  very  costly  to  make  of  a  forging, 
and  so  the  builder  must  turn  to  something  that  can  be  made 
in  a  mold,  and  that  means  an  annealed  steel  casting,  as  cast 
iron  cannot  escape  both  riskiness  and  clumsiness  at  the  same 
time. 

Fig.  100  shows  the  steel  forged  cross  head  now  passing  away, 
with  all  of  its  beauty,  finish,  and  mechanical  grace.     Fig.  101 


CROSS  HEADS  313 

shows  the  cast  steel  cross  head  with  its  intense  practicability 
both  as  to  low  cost  and  adaptation  to  the  more  economical  con- 
struction, although  it  cannot  entirely  hide  its  tendency  towards 
a  clumsy  appearance.  But  handsome  is  as  handsome  does, 
so  long  as  the  design  is  accurately  proportioned  and  the  steel 
casting  properly  annealed. 

Cross  head  shoes  are  made  mostly  of  brass,  of  cast  iron, 
and  of  cast  steel;  with  various  means  provided  for  adjusting 
for  wear  on  the  guides,  mostly  of  the  wedge  type,  controlled 
by  set  screws  and  binding  bolts.  The  most  general  and  likely 
the  best  practice,  is  to  have  cast  iron  guides  and  babbitt  faced 
shoes,  with  the  surfaces  so  proportioned  as  to  bring  the  pres- 
sure resulting  from  the  angular  position  of  the  connecting  rod 
at  each  stroke  below  25  Ibs.  per  square  inch  of  the  wearing 
surface  of  the  shoe. 

There  are  other  forms  of  cross  heads  for  pumping  engines, 
than  those  herein  shown,  more  or  less  special  for  special  situa- 
tions; but  these  are  the  ones  generally  used,  and  as  they  give 
excellent  satisfaction  and  are  at  least  as  low  in  cost  of  produc- 
tion and  operation  as  can  likely  be  made  for  a  good  article,  they 
will  probably  continue  in  practice  in  this  line  of  work  for  a  long 
time  to  come. 

The  form  of  the  cross  section  of  the  guide  at  the  surface 
where  the  shoe  slides,  is  made  in  various  forms:  the  "V"  shape; 
circular  like  the  interior  of  a  cylinder;  and  flat.  These  are 
the  principal  forms,  with  the  circular  probably  predominating 
in  the  latest  practice,  or  during  the  past  fifteen  years  or  so. 


CHAPTER   XXIY 
FRAMES   AND   BEDPLATES 

To  make  a  general  statement  of  the  case  in  hand:  the  force 
and  motion  derived  from  heat  are  modified  and  transmitted 
by  a  pumping  engine  in  doing  the  work  of  pumping  water. 
And,  viewed  broadly  as  a  machine  doing  work,  the  pumping 
engine  may  be  divided  into  two  principal  classes  of  parts; 
the  framing  and  bedplates,  or  non-moving  or  structural  parts, 
and  the  mechanism  or  working  or  moving  parts.  The  frames 
and  bedplates  provide  support  for  the  moving  parts  and  to  a 
considerable  extent  control  their  movements. 

In  the  operation  of  a  pumping  engine,  the  things  that  are 
done  or  accomplished  are: 

a.  A  natural  source  of  energy,  as,  for  example,  heat,  gives 
out  force  and  communicates  action  or  movement  to  the  work- 
ing parts. 

b.  The  force    and   motion  so    derived  from    the    source    of 
energy  are  transmitted  through    the  piston  and  plunger  rods 
to  the  water  plungers  within  the  pumps,  in  a  proper  an'd  suit- 
able manner  and  amount,  to  do  the  work  for  which  the  engine 
is  designed. 

c.  The  water  plungers,  or  the  real  working  members  of  the 
machine,  by  means  of  their  force  and  action  together,  pump 
the  water  against  the  pressure  and  in  the  quantity  for  which 
the  pumping  engine  is  constructed. 

The  strength  of  the  materials,  the  most  suitable  materials  to 
be  used,  the  manner  of  their  use,  and  the  necessary  dimen- 
sions, in  order  that  risk  of  breakage  and  overstraining  may 
be  avoided  so  far  as  practicable  in  the  regular  work  of  the 
machine,  while  undergoing  the  greatest  straining  action  called 

314 


FRAMES  AND  BEDPLATES  315 

for  by  the  work  being  done,  are  to  be  carefully  determined  in 
order  that  a  pumping  engine  may  be  fit  for  use  in  regular  water 
works  service  for  long  periods  of  time. 

The  proper  materials,  then,  for  the  various  classes  and  parts 
of  pumping  engines  having  been  selected,  the  work  of  construc- 
tion consists  in  forming  and  shaping  the  various  parts  to  the 
dimensions  and  plans  of  the  design,  by  means  of  proper  pro- 
cesses, tools,  and  machinery,  and  then  fitting  and  seeming 
the  various  parts  together  so  as  to  form  a  complete  machine 
ready  for  work.  And,  as  this  chapter  is  devoted  to  frames 
and  bedplates,  those  parts  principally  will  be  dealt  with  at 
present. 

The  framing  of  horizontal  and  of  vertical  pumping  engines 
differ  very  radically  from  each  other,  in  form  and  use.  In  a 
horizontal  machine  the  steam  cylinders  and  water  cylinders 
are  supported  directly  from  the  foundations  without  any  assist- 
ance from  the  frames ;  the  frames  acting  only  to  hold  the  steam 
and  water  ends  of  the  engine  in  proper  relation  with  each 
other  so  as  to  give  the  necessary  amount  of  resistance  to  the 
working  forces,  and  a  correct  design  will  bring  the  work  of  the 
engine  and  the  strains  on  the  frames  into  the  same  center  lines 
and  thus  make  the  machine  self  contained. 

The  definition  of  the  word  "Science"  is  "Knowledge  gained 
and  verified  by  exact  obvervation  and  correct  thinking,  or, 
obtained  individually  by  study  of  facts,  principles,  causes, 
etc.,"  and  engine  framing  certainly  requires  just  such  treat- 
ment if  it  is  to  be  put  in  the  right  place  and  made  in  the  proper 
form  and  strength. 

But  the  aim  of  the  engineer  in  designing  pumping  engines 
is  not  to  be  precisely  and  exactly  scientific  to  the  exact  limits 
of  the  conditions  imposed,  but  rather  to  make  his  work  so  it 
shall  be  SAFE,  as  a  first  consideration,  and  then  go  as  nearly 
to  the  exact  line  of  requirements  as  his  experience  finally 
teaches  him  he  can  scientifically  reach,  with  all  of  the  con- 
ditions weighed  and  accounted  for.  This  process  has  been 
put  into  one  short  sentence  by  a  very  eminent  engineer  and 


316  PUMPING  ENGINES 

designer  in  the  pumping  engine  line ;  "  if  it  is  too  strong  nobody 
knows  it,  but  if  it  is  too  weak  everybody  knows  it." 

In  the  beginning,  when  pumping  engines  were  built  mostly 
for  the  purpose  of  removing  water  from  mines,  the  framing 
did  not  amount  to  very  much  of  itself,  and  in  fact  the  walls 
of  the  building  covering  the  working  beam  were  sometimes 
used  really  as  framing.  The  Simpson  beam  pumping  engine 
was  constructed  with  complete  frames  and  bedplates,  and 
for  several  years  after  its  introduction,  from  1848  to  about 
1880,  it  seemed  to  be  necessary  to  build  large  pumping  engines 
upon  the  beam  and  fly  wheel  plan,  in  some  form  or  other,  and 
quite  a  number  of  special  designs  embodying  various  applica- 
tions of  framing  and  bedplates  were  introduced,  but  not  suffi- 
ciently repeated  to  comprise  a  type.  In  the  meantime  the 
Worthington  duplex  horizontal  pumping  engine  for  water 
works,  the  Holly  quadruplex  engine,  and  the  Gaskill  engine, 
had  been  designed,  repeated,  and  finally  took  place  in  the  regu- 
lar field  for  such  work  in  typical  form.  The  older  form  of  the 
Worthington  duplex  engine  and  of  the  Gaskill  engine,  both 
horizontal  machines  and  types  widely  known,  had  for  the 
framing  between  the  steam  and  water  ends,  polished  round 
bars  of  iron  or  steel ;  but  the  latter  engine  had  also  a  substan- 
tial bedplate  extending  beneath  each  side  of  the  machine  which 
no  doubt  greatly  stiffened  and  strengthened  the  engine,  and 
was  probably  necessary  in  a  crank  and  fly  wheel  machine  with 
such  light  weight  connecting  members.  The  old  fashioned 
non-rotative  machine  on  the.  other  hand,  with  its  entire  absence 
of  heavy  revolving  or  vibrating  parts,  no  doubt  made  out  well 
enough  with  the  round  bar  framing.  At  all  events,  most  of 
them  have  lasted  many  years  in  good  order.  In  the  original 
Gaskill  engine  there  was  also  a  cast  iron  girder  extending  from 
the  high  pressure  cylinder  at  each  side  of  the  engine  to  the 
middle  of  the  length  of  each  water  cylinder,  at  the  top  of  the 
force  chambers,  to  which  were  attached  the  main  pillow  blocks 
for  the  crank  shaft. 

The  framing  of  the  later  Gaskill,  and  of  the  high  duty  Worth- 


FRAMES  AND  BEDPLATES  317 

ington  engines,  are  composed  of  comparatively  heavy  and  cer- 
tainly very  strong  cast  iron  girders;  in  the  use  of  "which  in  the 
former  engine  the  bedplates  have  been  discarded  and  both 
steam  and  water  cylinders  set  directly  and  secured  upon  the 
tops  of  the  foundation  piers. 

The  framing  of  the  Holly  quadruplex  engine  was  in  the  "  A"- 
form,  with  the  main  crank  shaft  at  the  top  of  the  "A"  and 
the  center  lines  of  the  steam  and  water  cylinders  at  an  angle; 
the  main  pumps  were  located  immediately  behind  and  below  the 
steam  cylinders,  with  struts  or  distance  pieces  to  keep  the 
water  and  steam  cylinders  in  correct  alignment  and  distance. 

Fig.  102,  Fig.  103,  and  Fig.  104  show  the  framing  of  the  Holly 
quadruplex,  and  the  later  frames  of  the  Worthington  and 
Gaskill  engines. 

In  quite  recent  years  a  design  of  crank  and  fly  wheel  pump- 
ing engine  known  as  the  horizontal  cross  compound  has  come 
to  the  front  as  a  pronounced  type,  although  cross  compound 
steam  engines  and  an  occasional  cross  compound  pumping  engine 
have  been  known  for  a  long  time.  An  attempt  was  made  a 
good  many  years  ago  to  produce  the  Worthington  engine  in 
the  form  of  the  cross  compound,  and  called  the  tank  engine 
from  the  fact  that  what  is  now  known  as  the  receiver,  was 
known  by  the  name  of  the  tank,  or  at  least  so  designated  by 
the  builders  of  the  non-rotative  machine.  Several  of  these 
tank  engines  were  constructed,  but  the  delicacy  of  balance 
between  the  two  sides  of  the  machine  necessary  for  good  results 
in  the  crankless  engine,  could  not  be  obtained  where  the  steam 
was  entirely  let  go  of  by  one  side  and  taken  up  again  by  the 
other  side.  In  a  crank  engine,  the  two  sides  of  the  machine 
are  held  at  all  times  in  proper  relation  with  each  other  by 
means  of  the  absolute  control  of  the  moving  parts  by  the  cranks, 
and  a  little  surplus  power  by  one  side  or  the  other  did  not  matter, 
as  the  shaft  and  wheel  took  care  of  all  irregularities  when  they 
occurred. 

The  Allis-Chalmers  Company,  the  Platt  Iron  Works  Com- 
pany, and  the  Snow  Steam  Pump  Company  have  brought  out 


318 


PUMPING  ENGINES 


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FRAMES  AND  BEDPLATES 


319 


320  PUMPING  ENGINES 

very  effective  and  substantial  machines  of  the  cross  compound 
type,  and  they  consist  really  of  cross  compound  Corliss  steam 
engines,  connected  to  two  water  cylinders  by  means  of  very 
heavy  framing  secured  to  the  foundation  by  means  of  anchor 
bolts.  The  main  pumps  in  the  Allis-Chalmers  and  Snow 
engines  are  situated  at  opposite  ends  of  the  frames  from  the 
steam  cylinders,  and  in  direct  line  with  them.  The  water  cyl- 
inders and  the  steam  cylinders  are  firmly  bolted  directly  to  these 
engine  frames  of  a  deep  box  pattern;  and  a  direct  and  rigid 
driving  connection  is  made  between  the  steam  pistons  and  the 
water  plungers  by  means  of  heavy  steel  distance  rods,  which 
connect  piston  and  plunger  cross  heads  at  opposite  ends  of  the 
framing;  the  cross  heads  at  the  steam  end  being  coupled  to 
the  connecting  rods  for  driving  the  cranks,  which  are  pressed 
and  keyed  on  to  the  ends]  of  the  main  shaft  at  an  angle  of 
90  degrees. 

The  cross  head  guides  in  all  three  of  these  engines  are  formed 
in  the  frames  in  a  very  solid,  effective  manner;  and  the  main 
pillow  blocks  are  also  cast  as  a  portion  of  the  frames  where  they 
are  broadened  out  for  their  accommodation.  The  fly  wheel  is 
located  mid-way  between  the  two  main  frames,  and  in  the 
Allis-Chalmers  and  Snow  engines,  about  in  the  middle  of  the 
machine,  both  crosswise  and  lengthwise.  This  type  of  pumping 
engine  requires  considerable  floor  space  in  proportion  to  capac- 
ity, but  it  is  a  very  effective  and  satisfactory  machine,  com- 
bining as  it  does  a  reasonably  high  economy  of  steam  with  a 
moderate  price. 

Fig.  105  shows  the  Allis-Chalmers  engine,  Fig.  106  shows  the 
Platt  Iron  Works  engine,  and  Fig.  107  shows  the  Snow  engine, 
illustrating  the  peculiar  form  of  framing,  and  other  details. 

This  present  typical  cross  compound,  horizontal  pumping 
engine,  is  no  doubt  a  very  good  investment  for  pumping,  up 
to  a  few  hundred  horse  power;  and  of  course  with  the  horse 
power  limited,  which  it  must  be  on  account  of  the  horizontal 
cylinders,  its  capacity  will  depend  upon  the  pressure  against 
which  it  is  to  work.  Its  cost  is  comparatively  low,  and  its 


4 


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PH 

3 

S 
O 

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3 


bo 

1 


bo 

£ 


Fig.  105.  —  Allis-Chalmers  Cross  Compound  Framing. 


FRAMES  AND  BEDPLATES  321 

steam  duty  is  comparatively  high ;  in  fact,  its  duty  can  be  made 
about  as  high  as  any  compound  by  introducing  into  its  con- 
struction some  of  the  refinements  applied  to  the  vertical  triple 
expansion  machine,  as  in  the  case  of  the  Platt  Iron  Works 


Fig.  106. —  Flatt  Iron  Works  Cross  Compound  Framing. 

engine,  and  under  the  average  water  works  head  of,  say,  200  ft., 
the  cross  compound  machine  might  be  favored  up  to  10,000,000 
U.  S.  gallons  capacity.  On  the  direct  service,  er  on  the  stand- 
pipe  system,  where  there  is  no  storage  "by  the  use  of  reservoirs, 
by  calculating  the..maximum  capacity  of  the  engine  at  a  fairly 
good  piston  speed,  but  where  it  will  likely  run  at  not  much 


322 


PUMPING  ENGINES 


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B 


G 


o     o 

«©   © 


Fig.  108  —  Vertical  Pumping  Engine  with  two  Piers,  Holly  Mfg.  Co. 


FRAMES  AND  BEDPLATES  323 

more  than  half  speed  most  of  the  time,  a  satisfactory  capital 
economy  and  a  very  good  general  steam  economy  can  be 
effected. 

With  vertical  pumping  engines  the  framing  is,  as  may  be 
supposed,  entirely  different  from  that  of  the  horizontal  machine. 
In  the  early  days  of  the  present  type  of  vertical  pumping 
machinery,  say  twenty  years  ago,  the  pumps  were  placed  in 
a  pit  formed  by  the  massive  stone  or  brick  piers  which  made 
up  the  foundations  for  supporting  the  steam  end  bedplates,  and 
upon  the  tops  of  these  bedplates  the  framing,  mostly  of  the  "A" 
frame  type,  was  securely  bolted.  Of  the  crank  and  fly  wheel 
engines,  a  very  few  at  the  beginning  had  their  steam  cylinders 
located  upon  the  bedplate,  and  the  pillow  blocks  for  the  crank 
shaft  at  the  top  or  apex  of  the  "A"  frame,  but  'this  was  soon 
changed,  and  what  is  really  the  modern  marine  engine  with 
the  steam  cylinders  at  the  top  of  the  "A"  frame  and  the  pillow 
blocks  and  shaft  at  the  bedplate  level,  soon  came  to  the  front, 
and  the  present  vertical  engine  likely  will  remain  so  until  it 
is  supplanted  by  some  other  form  of  prime  mover,  not  yet  in 
sight. 

After  a  few  vertical  pumping  engines  had  been  built  and 
put  into  operation,  it  was  found  that  one  of  the  masonry  piers 
could  be  dispensed  with,  and  one  end  of  the  main  bedplates 
could  be  supported  on  the  tops  of  the  pump  chambers,  thus 
making  the  machine  partly  self-contained;  and  this  change 
also  made  everything  about  the  main  pumps  more  accessible. 
Later  on  still  another  change  was  made,  and  the  entire  machine 
was  made  self-contained,  by  using  "A"  frames  extending  from 
sole  plates  at  the  bottom  of  the  structure,  and  upon  these  sole 
plates  were  bolted  the  main  pumps.  The  frames,  just  about  where 
the  cross  bar  of  a  capital  letter  "A"  would  be  located,  are  inter- 
cepted by  the  steam  end  bedplates;  then  the  frames  extend 
upward  until  the  rather  broad  apex  or  top  of  the  "A"  is  reached, 
where  the  steam  cylinders  are  located. 

Fig.  108  and  Fig.  109  show  the  vertical  crank  engine,  with 
two  masonry  piers,  and  also  with  one  pier.  Fig.  110  shows 


324 


PUMPING  ENGINES 


Fig,  109.  —  Vertical  Pumping  Engine  with  one  Piere 


f 

FRAMES  AND  BEDPLATES 


325 


the  vertical  engine  with   the  '"A"  frames  extending  from   the 
bottom  of  the  water  end  to  the  steam  cylinders. 
So  far,  or  up  to  about  eight  years  ago,  what  is  known  as  the 


Fig.  110.  —  Vertical  Pumping  Engine  with  all  "A"  Frame. 

double  "A"  frame  had  been  used,  but  about  that  time  a  still 
nearer  approach  to  the  later  marine  construction  was  made, 
and  the  double  "  A"  frame  gave  way  to  the  single  "A"  frame,  which 
maintained  all  of  the  principal  constructive  effects  but  made  a 


320  PUMPING  ENGINES 

much  neater  and  in  some  ways  a  more  accessible  engine  frame. 
The  adoption  of  the  single  frame  made  it  rather  awkward  to 
use  a  double  frame  below  the  steam  bedplates,  and  so  another 
change,  which  looks  as  though  it  might  be  a  final  one,  is  to 
support  the  entire  steam  part  of  the  machine  from  the  steam 
bedplates  up,  on  top  of  the  valve  or  air  chambeis  of  the  main 
pumps.  The  main  pumps  are  suppoited  upon  sole  plates  in 
the  basement  of  the  engine  room,  and  for  all  ordinary  depths 
of  basement  possible  to  obtain  in  pumping  stations  this  type  of 
pumping  engine  will  answer. 

This  construction,  as  a  whole,  is  very  effective  and  substan- 
tial, neat  and  symmet.ical.  And  so  fa;1  as  can  now  be  seen,  this 
self-contained,  solidly  appearing,  and  ieally  very  solid  type 
of  pumping  engine  of  the  triple  expansion  class  is  quite  the 
limit  of  perfect  design  and  construction  of  crank  and  fly  wheel 
machinery  for  large  engines. 

Fig.  Ill  is  a  good  representative  illustration  of  this  machine, 
and  aside  from  admirable  a:rangement  of  bedplate  and  frames 
the  various  other  details  may  be  seen  to  be  most  fittingly 
adapted  in  the  general  design.  There  a:e  no  foundations 
required  excepting  a  level  and  substantial  bottom  in  the  engine 
house  basement,  resting  upon  lock  preferably,  but  any  good 
soil  with  the  pressures  properly  sustained,  using  piling  if  neces- 
sary,  will  answer  the  purpose. 

This  design  is  also  very  satisfactory  as  a  cross  compound^ 
vertical  pumping  engine,  by  simply  leaving  off  a  third  of  the 
design,  using  one  high  pressure  and  one  low  pressure  cylin- 
der, two  frames,  two  bedplates,  one  shaft  and  wheel,  and  two 
of  the  main  pumps.  In  such  a  case  if  these  lines  were  followed 
closely,  the  two  pumps  would  have  to  be  coupled  with  cranks 
set  opposite  each  other,  or  set  with  the  crank  p!ns  180  degrees 
apart,  on  account  of  the  single  acting  plungers  which  must 
act  directly  opposite  each  other.  Such  a  cross  compound 
would  do  very  good  service  on  reservoir  work,  where  the  force 
main  had  no  connections  with  the  service  pipes  of  consumers. 

The  double  "  A "  frame  engine  has  been  built  also  in  the 


.    -I 


Fig.  111.  —  Latest  Type  of  Self-contained  Engine,  Irving  H.  Reynolds. 


FRAMES  AND  BEDPLATES  327 

cioss  compound  form;  with  the  single  masonry  p'er,  and  also 
with  the  completely  self-contained  "A"  framing.  In  this  form, 
small  and  moderate  sized  compound  engines  have  been  bu'lt, 
and  also  so  large  as  to  have  50  inch  high  pressure  and  92 
inch  low  pressure  cylinders,  with  64  inches  stroke;  also  with 
27  inch  high  pressure,  52  inch  low  pressure,  and  with  108 
inches  stroke. 

The  Worthington  triple  expansion,  high  duty  vertical  engines 
have  been  built  as' large  as  20,000,000  U.  S.  gallons  daily 
capacity,  and  a  few  even  larger  than  this.  In  this  type  the 
framing  is  somewhat  of  the  "A"  form,  although  not  so  clearly  p;  o- 
nounced  as  in  some  other  types;  there  are  generally  no  bed- 
plates, but  the  feet  of  the  frames  are  secured  by  heavy  anchor 
bolts  to  the  tops  of  the  masonry  piers  between  which  the  main 
pumps  are  located  in  a  sort  of  pit  formed  between  the  piers. 
These  piers  rest  upon  a  sub-foundation  usually  of  concrete 
upon  which  the  main  pumps  are  secured;  thus  the  engine  piers 
really  form  a  portion  of  the  framing. 

In  a  late  design,  the  entire  engine  is  placed  upon  a  sole  plate 
with  "A"  frames  extending  from  the  sole  plate  to  the  steam 
cylinders  at  the  top  of  the  construction,  and  so  the  machine 
is  completely  self-contained,  in  this  respect  differing  from  the 
first  verticals  of  this  type. 

It  is  curious  to  note  in  this  connection  how  several  of  the 
makers  of  large  pumping  engines  have  been  mistaken  at  dif- 
ferent times  and  unknown  to  each  other,  regarding  the  needs 
of  a  rigid  frame  connection  between  the  steam  and  water 
ends;  and  the  writer  recalls  curiously  enough  also,  that  in  his 
own  experience  he  observed  and  assisted  in  adjusting  this 
error  in  two  different  widely  separated  cases,  involving  two 
of  the  largest  builders  of  pumping  machinery  at  the  different 
times.  The  first  was  a  case  of  three  single  acting,  outside 
packed  plungers  located  in  independent  plunger  barrels  at 
the  bottom  of  a  masonry  pit  formed  by  the  foundations.  It 
had  been  calculated  that  these  plunger  barrels  were  to  be  placed 
upon  solid  stone  masonry  at  the  bottom  of  the  foundations, 


328  PUMPING  ENGINES 

and  that  as  the  thrust  of  discharge  was  always  downward, 
and  that  the  suction  lift  was  almost  nothing  when  compared 
with  the  weight  of  the  plunger  barrels,  to  say  nothing  of  the 
fact  that  the  plunger  barrels  were  heavily  bolted  to  the  valve 
chambers,  making  a  great  mass  of  iron  castings  weighing 
many  tons.  But  there  was  no  frame  connection  from  the 
plunger  barrels  to  the  steam  end  bedplates  at  the  top  of  the 
foundations,  it  being  presumed  that  none  would  be  needed. 
Nevertheless  with  all  appearances  in  favor  of  satisfactory 
action,  there  was  enough  relief  upon  the  stonework  under 
the  plunger  barrels  during  the  suction  stroke,  to  cause  a  decided 
downward  thrust  during  the  delivery  stroke,  and  enough 
vertical  action  took  place  to  begin  to  wear  the  masonry  seat 
of  the  plunger  barrels,  promising  in  a  short  time  to  throw  the 
machinery  out  of  line  by  unevenness  of  the  foundations.  The 
remedy  applied  was  to  put  connecting  struts  between  the  steam 
bedplates  at  the  top  of  the  pit  and  the  plunger  barrels  at  the 
bottom,  and  so  placing  something  to  resist  the  working  forces 
in  the  center  plane  of  motion. 

The  other  case  was  a  very  large  vertical  non-rotative  pump- 
ing engine,  with  two  double  acting  plunger  pumps  at  the  bot- 
tom of  the  pit  formed  by  the  foundation  piers,  the  steam  end 
of  the  machine  being  supported  upon  "A"  frames  from  the 
tops  of  these  piers,  and  without  any  framing  connection  be- 
tween the  steam  and  water  ends.  It  had  been  calculated  that 
the  immense  weight  of  the  water  ends  would  make  all  such 
connections  unnecessary,  but  a  short  time  at  work  demon- 
strated that  the  concrete  foundation  beneath  the  main  pumps 
was  beginning  to  give  way,  and  it  finally  had  to  be  replaced, 
and  reinforced  by  heavy  steel  "  I  "  beams.  Therefore  it  would 
seem  that  as  an  absolute  principle  of  construction,  in  pump- 
ing engines  at  least,  and  probably  in  all  prime  movers,  there 
must  be  a  rigid  frame  connection  between  the  power  and 
the  work,  central  with  the  lines  of  force. 

Fig.  112  shows  the  Worthington  vertical  triple  expansion 
pumping  engine,  and  indicates  the  arrangement  of  the  fram- 


f         . 

FRAMES  AND  BEDPLATES 


329 


ing,  and  the  positions  of  the   steam  and  water  ends -of  the 
machine. 

It  being  necessary  in  the  non-rotative  type  to  have  a  pump- 
ing engine  which  will  make  four  strokes  to  a  "revolution"  or 
cycle,  the  main  pumps  have  to  be  double  acting,  and  the  upward 
discharge  stroke  exerts  a  very  considerable  upward  pressure  upon 


Fig.  112. —  Framing  of  Worthington  Vertical  Triple  Engine. 


the  main  pump  casting,  in  this  case  a  great  many  tons,  which 
although  rather  a  long  way  short  of  the  weight  of  the  water 
cylinder,  is  nevertheless  quite  sufficient  to  cause  an  upward  and 
downward  vibration.  The  action  of  such  a  performance  would 
resemble  somewhat  the  treading  of  an  enormous  cast  iron 
elephant,  weighing  perhaps  50  or  60  tons;  and  any  one  at  all 
conversant  with  concrete  and  masonry,  would  know  how  damag- 
ing it  would  likely  be.  The  placing  of  struts  and  tic  bolts 
between  the  steam  and  water  ends  in  the  line  of  the  work, 


330  PUMPING  ENGINES 

would  make  the  machine  self-contained  and  avoid  such  bad 
effects  upon  the  foundation. 

In  connection  with  this  branch  of  the  subject,  there  natu- 
rally comes  the  matter  of  galleries,  platforms,  stairways,  and 
more  or  less  complete  facilities  for  getting  around  the  engine, 
at  rest  and  in  motion.  There  should  be  a  substantial  and 
permanent  iron  platform  around  and  about  the  upper  ends  of 
the  main  plunger  barrels  for  vertical  engines,  at  a  convenient 
height  for  easily  and  safely  reaching  the  gland  bolts  and 
plunger  packing,  when  necessary  to  renew  or  take  up  the 
packing. 

The  main  floor  of  the  engine  room  will  provide  means  for 
manipulating  the  throttle  valve,  condenser  valves,  priming 
valves,  and  other  necessary  facilities  for  starting  and  running 
the  engine.  Then  a  platform  at  the  base  of  the  steam  cylin- 
ders on  moderate  sized  engines,  and  in  addition  to  this  a  plat- 
form half  way  up  the  frames  on  large  engines;  also  on  the  laiger 
machines  there  is  need  of  a  platform  somewhere  near  the  tops 
of  the  steam  cylinders. 

With  horizontal  pumping  engines  there  is  no  need  of  so  many 
platforms,  but  some  a.-e  necessary  for  the  larger  sizes;  and  with 
large  Gaskill  and  Worthington  engines,  especially  for  the 
former,  a  platform  extending  the  entire  length  on  both  sides 
and  back  of  the  steam  cylinders,  located  about  at  the  base  of 
the  high  pressure  cylinder,  is  very  useful  and  convenient  for 
those  who  have  to  be  about  the  engine.  With  the  Worthington 
and  large  cross  compound  engines,  a  biidge  platform  ac  oss 
the  machine,  and  facilities  for  reaching  the  valve  stems,  gauges, 
and  other  details  are  usually  provided. 


CHAPTER   XXV 

MATERIAL   FOR   PUMPING  ENGINES 

IN  this  age  and  day  when  skilled  practice  of  wide  range,  and 
good  business  management,  for  foundry,  forge,  and  machine 
shop,  have  been  brought  to  a  very  high  stage  of  perfection, 
the  price  of  a  high  class  economical  pumping  engine  has  been 
reduced  to  a  point  which  justifies  the  use  of  a  very  high  steam 
economy  in  pumping  water.  A  much  better  engine  can  be 
installed  now  than  most  people  would  buy  a  few  years  ago; 
an  engine  in  which  is  combined  simplicity,  high  efficiency, 
great  durability,  and  compactness.  In  fact,  a  high  type  of 
pumping  engine  is  now  used  in  the  comparatively  small  capaci- 
ties, which,  not  so  very  long  ago  were  left  to  the  field  of  low 
economy  and  low  interest  account.  It  may  be  that  piofits 
are  less;  but  production  is  certainly  less  costly;  several  factois 
no  doubt  conspiring  to  help  the  buyer. 

In  no  direction  probably  has  there  been  so  much  impiove- 
ment  in  the  line  of  material  and  workmanship  as  in  the  crank 
shaft  and  similar  details  of  rotative  engines.  For  use  in  the 
construction  of  crank  and  fly  wheel  pumping  engines  the  eco- 
nomical production  of  the  very  highest  quality  of  solid  open 
hearth  steel  forgings,  and  center  forged  steel  details  for  steam 
machinery  has  gradually  brought  the  grade  of  various  parts  of 
pumping  engines  up  to  the  highest  known  level  for  such  woik. 
Although  costing  a  moderate  percentage  -more  than  wrought 
iron,  the  very  best  and  really  cheapest  material  for  piston 
rods,  connecting  rods,  crank  shafts,  distance  rods,  and  other 
details  of  like  nature,  is  steel;  forged  under  hydraulic  perssure 
from  clean,  sound  ingots  somewhat  larger  in  mass  than  the 
finished  product,  and  the  piece  properly  annealed.  Such 

331 


332 


PUMPING  ENGINES 


fcLgings  not  infrequently  have  a  tensile  strength  of  over  80,000 
Ibs.,  and  an  elastic  limit  of  50,000  Ibs.  with  an  elongation  of 
25  per  cent  before  paiting. 

Open  hearth  furnaces  with  temperatures  of  about  4,000  F. 
are  used  for  steel  ingots  necessary  for  making  such  shafts, 
rods,  etc.  The  best  forging  is  mostly  done  in  hydraulic  presses 
at  quite  a  moderate  rate  of  "  squeezing  "  which  allows  the  flow 
and  adjustment  of  the  metal  to  take  place.  Sometimes  gross 
pressures,  of  from  12,000  to  14,000  tons,  are  employed  in  this 
hydraulic  forging  process,  and  from  400,000,000  to  600,000,000 
foot  pounds  per  minute  are  developed;  the  actual  force  in  the 
pressure  pumps  reaching  as  high  as  6,500  Ibs.  per  square  inch. 
During  the  process  of  forging  a  hollow  steel  shaft  inside  and  out, 
the  material  is  thoroughly  compacted,  as  the  mandiil  almost 
fills  the  hole  in  the  ingot  and  serves  as  a  sort  of  anvil,  a  succes- 
sion of  pressures  taking  the  place  of  the  blows  in  ordinary 
steam  hammer  forging;  the  process  being  naturally  assisted  by 
the  advantages  in  heating  a  hollow  cylindrical  mass  instead  of 
a  solid  one.  The  undesirable  qualities  in  the  fluid  compressed 
steel  ingot  are  in  the  center,  and  after  the  original  casting  of 
the  ingot  is  made  the  defects  are  *  bored  out  after  cooling,  and 
the  sound  piece  in  the  form  of  a  short  thick  cylinder  is  reheated 
for  forging;  so  that  the  material  which  is  actually  worked  upon 
for  the  finished  product  is  practically  homogeneous,  or  alike 
in  quality  throughout. 

Solid  forgings  are  often  used  instead  of  the  hollow  forgings 
described  above,  and  very  good  material  may  be  produced, 
especially  of  the  dimensions  used  in  pumping  engines.  Some 
work  of  this  character  for  large  pumping  engines  was  tested  by 
the  writer  during  the  past  year  with  the  following  results;  the 
records  here  given  are  taken  at  random  from  a  number: 


DESIGNATION 

OF 

SPECIMEN. 

SQUARE  INCH, 
ELASTIC  LIMIT, 
POUNDS. 

SQUARE  INCH, 
TENSILE 
STRENGTH, 
POUNDS. 

ELONGA- 
TION, 
PER  CENT. 

REDUCTION 

OF 

AREA. 

A 

35  300 

76,250 

25 

39 

B    ..... 

C    

33,150 
33,250 

77,950 
75,350 

27 
27 

37 

37 

MATERIAL  FOR  PUMPING  ENGINES  333 

The  cranks  are  also  very  important  members  of  the  constiuc- 
tion  and  are  made  of  cast  iron,  wrought  iron,  or  steel,  mostly 
the  latter  in  the  later  and  better  machines,  according  to  cir- 
cumstances and  the  ideas  of  the  designer.  Cranks  are  some- 
times forced  on  to  the  shaft  by  hydraulic  pressure  or  in  a  screw 
p. ess,  and  are  sometimes  shrunk  on.  The  fly  wheel  hubs  are 
also  subjected  to  the  same  treatment,  mostly  forced  on  when 
the  wheel  is  made  with  a  center  or  hub  instead  of  in  halves  as 
is  often  done.  Wheels  in  halves  are  of  course  admissible,  but 
are  not  nearly  so  good  as  the  built  up  wheel  with  a  solid  hub 
put  into  place  upon  the  shaft  before  the  cranks  are  forced  into 
place.  The  fly  wheel  built  up  in  sections  and  bolted  between 
the  two  discs  forming  the  hub  by  through  bolts  having  a 
diiving  fit  in  reamed  holes  is  the  best  work  in  this  line;  the 
rim  is  made  in  sections,  generally  eight,  one  arm  bolted  into 
the  hub  for  each  section,  and  the  sections  of  the  rim  are  gen^ 
erally  held  together  at  their  ends  by  means  of  forged  links  set 
into  sockets  at  the  sides  of  the  wheel  rim,  the  links  having 
been  heated  and  allowed  to  cool  and  shrink  in  place.  This 
form  costs  the  most  of  any,  the  wheel  made  in  halves  being  the 
other  extreme  as  to  cost  and  desirability;  the  wheel  in  halves  is 
a  fairly  good  one  when  well  made,  especially  if  the  place  of* 
parting  is  planed  and  bolted  instead  of  being  cast  as  one  wheel 
and  then  broken  in  halves.  A  very  good  compromise  between 
these  two  wheels,  and  costing  somewhere  between  the  two 
types,  is  to  have  the  solid  hub  forced  on  to  the  shaft  with  discs 
separated  for  the  arms  the  same  as  for  the  built  up  wheel,  and 
then  have  the  rim  made  in  two  sections  like  the  wheel  in  halves, 
the  rim  secured  by  means  of  links  the  same  as  the  eight  section 
wheel;  the  difference  being  that  there  are  four  arms  to  a 
section  instead  of  one  arm. 

In  the  best  class  of  work,  the  pressing  fits  are  generally  ten 
tons  pressure  for  each  inch  diameter  of  shaft  or  crank  pin  or 
wheel  hub  seat,  the  wheel  centers,  cranks  and  crank  pins;  as, 
for  example,  a  shaft  16  inches  diameter  would  require  160 
tons  pressure  to  force  on  a  crank  or  wheel  center ;  or  for  a  crank 


334  PUMPING  ENGINES 

pin  say  8  inches  diameter,  a  pressure  of  80  tons  would 
be  required;  for  other  parts  requiring  forcing  fits,  the  pressure 
is  used  according  to  the  experience  and  practice  in  any  par- 
ticular line  of  the  shop  doing  the  work. 

Regarding  the  dimensions  of  crank  shafts,  practice  vaiies; 
but  the  best  and  strongest  work  in  the  line  of  crank  and  fly 
wheel  pumping  machinery  follows  rather  closely  the  lines  of 
power  engines  in  relation  of  shaft  diameter  to  horse  power 
and  speed.  The  work  of  the  pumping  engine  is  largely  done 
directly  from  the  pistons  to  the  plungers;  and  in  the  non-:o- 
tative  engines  of  the  low  duty  class  all  of  the  work  goes  directly 
to  the  plungers;  in  a  non-rotative  high  duty  engine,  as,  for 
example,  the  Worthington,  the  surplus  power  at  the  beginning 
of  the  stroke  goes  into  the  compensating  cylinders  and  through 
them  lifts  the  accumulator  piston,  this  piston  in  effect  resem- 
bling a  large  pneumatic  dumb  bell,  or  a  dumb  bell  consisting 
of  air  pressure,  the  dumb  bell  returning  the  power  after  the 
compensating  plungers  pass  the  central  point  in  the  stroke. 
Even  the  equalizing  of  the  expanding  steam  pressure  is  accom- 
plished by  direct  pressures  and  without  transmission  through 
anything  like  a  shaft;  in  fact,  such  work  is  done  in  the  non- 
•rotative  machine  without  torque. 

In  the  crank  and  fly  wheel  pumping  engine,  however,  only 
a  portion  of  the  power  goes  directly  from  the  pistons  to  the 
plungers;  the  first  part  of  the  stroke,  when  there  is  a  surplus 
of  power,  sending  a  portion  of  the  work  to  the  wheel  to  be 
given  back  again  during  the  latter  part  of  the  stroke  when 
the  expanding  steam  is  below  the  working  requirements. 
Theoretically,  therefore,  as  all  of  the  work  is  not  transmitted 
through  the  shaft,  it  might  be  naturally  enough  supposed  that 
a  smaller  shaft  than  a  power  engine  requires,  would  answer 
for  a  pumping  engine,  but  in  the  latter  the  transmission  of 
the  power  to  and  from  the  wheel  is  a  rougher  sort  of  a  task 
than  simply  sending  small  installments  of  energy  into  a  steadily 
revolving  wheel  at  a  pretty  good  speed.  It  may  be  readily 
noted  that  the  dimensions  of  crank  shafts  in  pumping  engines 


MATERIAL  FOR  PUMPING  ENGINES  335 

just  about  correspond  to  the  result  of  recognized  foimulae 
fo.'  transmitting  power  by  shafts;  that  is,  the  shafts  are  appar- 
ently calculated  as  though  all  of  the  power  was  sent  thiough 
them;  and  in  fact  the  paiticular  work  they  have  to  do  when 
the  stubboin  attributes  of  water  a:e  considered,  is  no  doubt 
a  more  severe  t.  ial  to  the  material  even  with  only  a  moderate 
percentage  of  the  power  of  the  engine  actually  transmitted 
thiough  the  shaft  in  the  form  of  torque  or  twisting  strain.  At 
all  events,  if  in  the  tiiple  expansion  engine  the  crank  shafts, 
of  which  there  are  two,  a:e  consideied  as  each  taking  care  of 
half  the  power,  which  is  a  reasonable  idea  to  say  the  least, 
Rankine's  foimula  for  transmitting  power  by  a  shaft  gives 
just  about  the  diameter  that  experience  has  taught  the  build- 
ers will  produce  a  shaft  safe  for  such  a  machine.  If  the  same 
foimula  be  applied  to  a  cross  compound  engine  of  a  well  recog- 
nized make,  upon  the  supposition  that  the  shaft  is  to  be  able 
to  transmit  the  full  power,  the  actual  shaft  made  for  the 
machine  will  be  found  to  be  very  close  in  diameter  to  the  results 
of  the  formula.  But  aside  from  what  is  found  in  practice, 
the  Rankine  formula  will  be  found  to  give  a  safe  and  practical 
size  of  shaft  when  applied  to  pumping  engines. 

Although  perhaps  a  little  out  of  place  in  a  book  of  this  kind, 
the  above  mentioned  formula  is  so  interesting  that  it  is  given: 

H.P.  represents  foot  pounds  per  minute  of  the  horse  power 
of  the  engine;  found  by  multiplying  the  indicated  horse 
power  of  the  steam  cylinders  by  33,000. 

6.2832  is  the  ratio  between  the  length  of  the  radius  of  a  circle 
and  the  circumference  of  a  circle;  or  the  proportion  be- 
tween the  distance  from  the  center  to  the  outside  of  the 
shaft,  and  the  distance  around  the  shaft. 

E.PM.  represents  the  revolutions  which  the  engine  is  to 
make  per  minute  at  full  contract  speed. 

M  represents  the  mean  or  average  twisting  strain  or  stress 
under  which  the  shaft  is  placed  by  the  work  which  is 
done. 


336  PUMPING  ENGINES 

MM  represents  the  maximum  or  greatest  twisting  strain  or 
stress  under  which  the  shaft  is  placed  by  the  work  which 
is  done;  and  is  found  by  multiplying  M  by  12  for  the 
reason  that  6  is  ordinarily  taken  as  the  factor  of  safety  for 
materials  of  this  kind  for  the  mean  or  average  strain,  and 
this  factor  of  safety  6  is  doubled,  making  12  for  the  maxi- 
mum or  greatest  strain. 

A  represents  the  modulus  of  stress;  which  is  a  number 
that  measures  the  actual  value  of  the  material  for  use; 
or,  it  is  the  measure  of  the  force  required  to  break  a  sub- 
stance across,  as  compared  with  the  force  required  to 
•  break  a  bar  of  the  substance  one  inch  square.  This  value 
is  225  for  forged  steel. 

D  represents  the  diameter  of  the  shaft  in  inches. 
Then  the  formula  is: 


r JL.P, x  12i 

[6.2832  x  R.P.M.    ' 


I) 


And  this  interpreted  into  words  means  as  follows : 

In  this  example  the  horse  power  is  taken  at  800,  or  400 
for  each  shaft  of  a  triple  expansion  pumping  engine;  then, 
400  X  33,000  =  13,200,000  ft.  Ibs.  per  minute,  representing  the 
work  of  the  indicated  horse  power  or  the  H.P.  in  the  foimula. 

Then,  as  the  revolutions  per  minute  are  22.5,  which  rep- 
resents the  R.P.M.  in  the  formula,  this  number  is  multiplied 
by  6.2832,  which  gives  141.372,  by  which  the  13,200,000  already 
found  is  to  be  divided,  and  the  result  is  93,370  as  the  value 
of  M  in  the  formula. 

Then,  M  is  multiplied  by  12,  and  the  result  is  1,120,440, 
which  is  the  value  of  MM  in  the  formula. 

Then,  the  value  of  MM  or  1,120,440  is  divided  by  225,  the 
value  of  forged  steel  in  the  formula,  and  the  result  is  4,979.73, 
and  this  number  is  the  cube  of  the  diameter  of  the  shaft  in 
inches. 


MATERIAL  FOR  PUMPING  ENGINES  337 

Then,  extracting  the  cube  root  from  4,979.73,  as  this  number 
is  the  cube  of  the  diameter,  we  have  17.077  inches  as  the 
diameter  of  a  steel  forged  shaft  for  this  machine;  or,  say,  17 
inches  as  the  nearest  practical  machine  shop  size.  It  may 
be  noted,  that  a  recently  built  triple  pumping  engine  of  800 
horse  power  has  a  shaft  at  each  side,  18  inches  diameter  fo/  a 
short  space  at  the  middle  where  the  wheel  goes  on,  and  16 
inches  next  to  the  pillow  blocks,  which  is  a  rather  close  size 
for  17  inches  average. 

Still  another  triple  pumping  engine  by  a  different  builder 
of  500  horse  power,  or  250  for  each  shaft,  has  a  steel  forged 
shaft  at  each  side  15  inches  diameter,  and  the  formula  calls 
for  15.18  inches. 

Also  a  cross  compound  pumping  engine,  recently  tested 
by  the  writer  for  duty,  running  at  unusual  speed  and  under 
unusually  high  water  pressure,  and  altogether  presenting 
entirely  different  conditions  from  the  usual  practice,  the  horse 
power  was  1,200  and  the  speed  was  67  revolutions  per  minute. 
The  formula  calls  for  a  shaft  J  of  an  inch  larger  than  the  shaft 
found  in  the  engine. 

It  is  pretty  certain  that  the  Rankine  formula  was  not  used 
on  any  of  the  above  mentioned  engines,  but  it  is  very  certain 
that  experience  and  judgment,  based  upon  what  has  been 
done  and  observed  by  engine  builders,  have  established  a  rule 
for  shafts  which  arrives  at  the  same  conclusion  as  was  arrived 
at  by  the  most  eminent  authority  on  the  strength  of  materials. 
And  this  brings  again  to  mind  the  definition  of  science,  "  Knowl- 
edge gained  and  verified  by  exact  observation  and  correct 
thinking;  knowledge  gained  individually  by  study  of  facts, 
principles,  causes,  etc.;  the  habit  or  possession  of  exact  knowl- 
edge." 

Regarding  the  matter  of  cranks  and  crank  pins  for  the  fly 
wheel  pumping  engines,  the  best  are  made  of  the  forged  steel; 
practically  the  same  material  as  that  for  the  shafts,  which 
has  already  been  gone  into  at  some  length.  The  dimensions 
of  these  parts  differ  some,  but  not  very  much,  among  different 


338  PUMPING  ENGINES 

builders.  The  crank  pins  may  be  set  down  as  of  a  diameter 
and  length  which  will  produce  about  1,300  Ibs.  per  square 
inch  of  projected  area,  or,  in  other  words,  1,300  Ibs.  for  each 
square  inch  found  by  multiplying  the  diameter  by  the  length 
of  the  journal.  This  would  be  for  the  outer  or  end  crank  pins 
of  a  triple  machine;  and  the  middle  pin,  or  that  for  the  inter- 
mediate cylinder,  would  be  about  50  per  cent  greater  in  dia- 
meter than  the  outer  one,  or  those  for  the  high  and  low  piess- 
ure  cylinders,  with  the  length  of  the  journal  the  same  in  all. 

The  dimensions  of  the  cranks  vary  some  with  the  different 
builders,  and  even  the  same  builder  is  not  always  consistent 
among  different  sizes  and  powers  of  engines;  the  convenience 
of  manufacture  is  often  considered  first  where  a  departure 
from  some  standard  proportion  does  not  do  any  harm;  and 
on  account  of  convenience  or  economical  handling  of  the  work, 
sometimes  a  heavier  crank  may  be  put  on  than  would  be  calcu- 
lated from  the  exact  proportion  of  the  machine. 

However,  a  very  good  proportion  for  steel  forged  cranks 
would  be  as  follows: 

Main  hub  of  crank,  twice  the  diameter  of  main  journal. 
Thickness  of  hub,  to  be  0.65  of  diameter  of  main  journal. 
Crank  pin  head  of  the  crank,  twice  the  diameter  of  crank 

pin  journal. 
Thickness  of    crank   pin    head  of  crank,  1.125  times  the 

length  of  the  crank  pin  journal. 
Thickness  of  crank  arm,  1.125  times  the  length  of  crank 

pin  journal. 

Regarding  cross  sections  of  the  connecting  rods,  there  is 
also  considerable  variation,  but  a  very  good  rule  is  as  follows: 

Tensile  strain  at  neck  of  connecting  rod  not  more  than 

2,500  Ibs.  per  square  inch. 
Tensile   strain  through  the   smallest  section  of  head  or 

strap  2,200  Ibs.  per  square  inch. 

These  strains  are  based  upon  the  gross  effective  steam  press- 


MATERIAL  FOR  PUMPING  ENGINES  339 

ure  at  the  beginning  of  the  stroke,  found  by  multiplying  the 
area  of  the  piston  by  the  difference  in  pressure  per  square  inch, 
between  the  initial  and  counter  pressures.  In  any  multiple 
cylinder  engine  the  total  net  pressure  would  not  be  alike  in  all 
of  the  cylinders,  so  the  diameter  of  the  rod  and  the  dimen- 
sions of  the  strap  could  be  based  upon  the  greatest  strain  given 
by  any  one  cylinder,  and  then  the  other  rods  and  straps  made 
to  match  the  largest  one. 

In  connection  with  the  main  shafts,  the  main  pillow  blocks 
come  in  for  a  share  of  attention  in  this  chapter;  the  diameter 
and  length  of  the  bore,  the  form  of  construction  to  meet  dif- 
ferent conditions,  and  the  various  details  which  go  to  make  up 
a  suitable  and  satisfactory  bearing  for  the  main  shaft,  require 
careful  attention  and  a  clear  understanding  of  the  requirements. 

In  non-rotative  pumping  engines  of  the  low  duty  class,  of 
course  no  beaiings  are  required  beyond  those  for  rock  shafts, 
valve  motion  connections,  and  air  pump  levers.  In  the  high 
duty  class  of  the  non-rotative  type  of  machinery,  some  require 
substantial  pillow  blocks  for  the  trunnions  of  oscillating  or  com- 
pensating cylinders,  but,  take  it  all  together,  the  pillow  block 
question  is  not  a  very  serious  one  with  the  non-rotative  pump- 
ing machinery. 

In  the  better  forms  of  horizontal  cross  compound  pumping 
engines  from  3,000,000  U.  S.  gallons  capacity  per  24  hours, 
up  to,  say,  10,000,000  gallons,  although  this  type  seldom  goes 
so  high  in  capacity,  the  main  pillow  blocks  are  arranged  so  as 
to  take  up  wear  both  horizontally  and  vertically,  because  the 
thrust  of  the  engine  is  horizontal,  and  the  wear  from  the  weight 
of  the  fly  wheel,  shaft,  and  cranks,  is  downward.  A  general 
description  of  a  satisfactory  bearing  for  this  type  of  machine 
is  as  follows: 

The  main  frame  of  the  engine,  which  is  of  the  box  form,  pro- 
portionately deep  and  heavy,  extends  from  the  steam  cylinder 
to  the  water  cylinder  at  each  side  of  the  machine.  At  the 
inner  side  of  the  frame,  or  the  side  next  to  the  opposite  frame, 
the  pillow  block  pedestal  is  formed  as  a  part  of  the  frame  itself, 


340  PUMPING  ENGINES 

and  at  its  top  is  located  the  socket  or  jaw  for  holding  the  boxes 
or  shells  of  the  main  shaft  bearing  (see  Fig.  107).  The  jaw 
and  the  shells,  a  top  and  a  bottom  and  two  side  shells  for  each 
bearing,  are  generally  made  after  the  pattern  of  the  original 
Corliss  pillow  block  first  made  fifty  years  ago,  and  probably 
a  better  or  more  practical  bearing  was  never  made  for  a  shaft. 
The  top  of  the  jaw  is  planed  with  projections  which  engage 
with  the  gib  ends  of  the  pillow  block  cap,  thus  firmly  holding 
the  two  sides  in  proper  relation;  the  shells  in  which  the  lining 
metal  is  poured,  hammered,  and  bored  to  suit  the  shaft,  are 
independent  of  the  jaw  and  the  cap,  and  are  free  to  move  hori- 
zontally when  the  lost  motion  is  taken  up  by  means  of  a  wedge 
shown  back  of  the  quarter  box  towards  the  steam  end  of  the 
frame.  The  shells  can  also  swing  if  necessary  just  a  trifle, 
and  the  general  result  is  that  these  shells,  having  once  been 
bored  and  properly  fitted  to  the  shaft,  will  adjust  themselves 
to  the  journal  in  such  a  way  as  to  practically  avoid  all  ten- 
dency to  bind  the  journal ;  in  fact,  will  follow  up  changing  posi- 
tions of  the  journal  so  as  to  keep  in  line  with  it  at  all  times, 
in  such  a  manner  that  the  bearing  or  the  shaft  cannot  be  heated 
or  cut  unless  set  up  too  tightly  or  left  too  long  without  lubri- 
cation. This  bearing  can  be  taken  up  vertically  and  hori- 
zontally at  the  same  time,  or  each  way  separately  without 
interfering  with  the  other  adjustment. 

In  vertical  pumping  engines  both  large  and  small,  it  is  now 
the  general  practice  to  cast  the  lower  half  of  the  main  pillow 
block  in  the  engine  bedplate,  and  then  cover  it  with  a  heavy 
cap  formed  so  as  to  tie  together  the  ends  of  the  lower  half  by 
means  of  lips  or  gibs  formed  at  the  lower  outer  edges  of  the 
scap.  The  actual  bearing  boxes  or  shells  in  which  the  journal  of 
the  shaft  rests  and  revolves,  are  mostly  two  separate  and  remov- 
able pieces  from  the  main  part  of  the  pillow  block;  although 
in  some  cases  the  lower  half  is  prepared  for  the  shaft  solidly 
in  the  bedplate,  and  the  upper  half  or  cap  is  made  to  form 
the  shell  for  the  upper  part  of  the  bearing.  In  either  case, 
the  removable  shells  or  the  non-removable  bearing,  the  real 


MATERIAL  FOR  PUMPING  ENGINES 


341 


bearing  surface  for  the  shaft  is  made  of  some  sort  of  anti-Lic- 
tion  metal,  practically  an  extra  good  mixture  of  what  has 
been  long  known  as  babbitt  metal.  This  comparatively  soft 
metal  is  melted  and  poured  into  spaces  formed  for  it,  thus 
making  a  circular  surface  approximately  the  size  and  shape 
of  the  shaft  journal.  After  cooling,  this  lining  metal  is  thor- 
oughly hammered  and  condensed  in  its  place  and  then  accurately 
bored  to  suit  the  shaft.  A  system  of  grooves  a:e  cut  in  the 
surface  of  the  finished  bearing  to  distribute  the  oil  under, 
over,  and  about  the  journal.  The  arranging  and  cutting  Of 


Fig.  113.  — Main  Pillow  Block  for  Crank  Shaft. 

these  oil  grooves,  although  seemingly  a  minor  detail,  is,  like  a 
great  many  minor  details,  extremely  important  to  the  success 
and  economy  of  the  machine. 

In  vertical  engines  of  course  is  there  is  no  need  of  taking  up 
the  wear  and  lost  motion  in  more  than  one  direction,  which 


342  PUMPING  ENGINES 

is  veitical;  as  the  thrust  of  the  engine  and  the  weight  supported 
by  the  bearings  act  practically  in  veitical  lines  only.  The 
bolting  of  the  pillow  block,  the  distribution  of  the  strains  in 
the  cap,  and  the  facilities  for  removing  the  shells,  especially 
the  ander  shell,  so  as  to  make  as  little  delay  as  possible  in  the 
working  of  the  engine,  are  all  matters  which,  thoug'i  compara- 
tively small  in  themselves,  a:e  ielatively  of  enough  significance 
to  justify  the  most  careful  attention. 

Fig.  113  shows  a  side  view  and  plan  of  a  pillow  block  for  a 
veitical  pumping  engine  formed  within  the  bedplate,  and  in 
this  machine  the  bottom  of  the  pillow  block  where  the  lower 
shell  rests  is  made  circular,  so  as  to  roll  out  the  shell  by  simply 
taking  the  weight  of  the  shaft  upon  a  jack  screw  or  by  other 
suitable  means.  This  side  view  also  shows  the  strong  reinforce- 
ment in  the  bedplate  casting  where  the  depression  is  formed 
for  the  pillow  block. 

In  making  a  brief  and  general  summary  of  the  different 
kinds  of  materials  which  enter  into  the  construction  of  pump- 
ing engines,  it  goes  without  saying  that  they  should  be  of  the 
very  best  quality  practicable  to  obtain.  It  is  simply  impos- 
sible to  obtain  absolutely  perfect  iron  castings,  but  there  is  a 
practical  perfection  possible  to  obtain  from  a  well  regulated 
foundry,  and  engineers  and  inspectors  should  have  sufficient 
judgment  and  courage  to  arrive  at  a  fair  and  proper  conclu- 
sion where  the  integrity  of  a  casting  has  been  called  into  ques- 
tion. Where  even  heavy  and  large  castings,  the  loss  of  which 
is  serious  to  the  manufacturer,  have  some  part  or  parts  so 
defective  that  they  cannot  be  properly  remedied,  they  should 
be  rejected  by  the  buyer  or  his  representative.  But  where 
there  are  blemishes  only,  or  minor  defects  that  add  nothing 
to  the  risk  of  using  the  casting,  and  which  can  be  removed 
or  remedied  by  the  manufacturer,  there  should  be  no  hesitation 
in  accepting  such  a  casting. 

The  writer  recalls  to  mind  a  large  plunger  barrel  weighing 
about  8  tons,  for  a  pumping  engine,  where  the  lower  flange 
was  so  defective  from  "blow"  or  from  some  small  portion  of 


I 

MATERIAL  FOR  PUMPING  ENGINES  343 

the  mold  having  been  dislodged,  that  it  was  weakened  and 
defaced  to  an  extent  that  made  it  really  impossible  to  use.  A 
gieat  remonstrance  was  set  up  by  the  maker,  but  in  spite  of  all 
appeals  and  regrets  the  casting  was  rejected. 

In  another  case,  an  air  chamber  belonging  to  the  same 
class  of  machinery  and  weighing  probably  12  tons  or  so,  devel- 
oped a  bad  spot  in  the  face  of  the  bottom  flange  when  the 
facing  was  being  done.  After  the  roughing  cut  had  been  fin- 
ished, a  blemish  or  defect  appealed  in  the  face  of  the  flange 
about  8  inches  long,  2  inches  wide,  and  1  inch  deep.  As  the 
face  of  the  flange  was  about  7  inches  wide  and  this  rut  ex- 
tended in  a  circular  direction,  it  was  decided  after  testing  and 
examining  the  surrounding  metal,  to  have  a  piece  of  cast  iron 
fitted  and  driven  into  the  damaged  place  after  dressing  out  to 
sound  metal,  and  then  the  finishing  cut  for  the  facing  work 
was  completed.  The  flange  was  diilled  for  the  bolt  holes, 
and  after  a  short  time  it  was  very  difficult  to  locate  the  blemish. 
This  casting  was  then  accepted  for  use  in  the  engine. 

The  cast  iron  for  fly  wheels,  bedplates,  frames,  etc.,  having 
a  tensile  strength  of  18,000  to  20,000  Ibs.  per  square  inch,  or 
a  cross  breaking  resistance  of  one  tenth  of  these  figures,  with 
usual  size  bars,  would  be  acceptable  for  pumping  machinery; 
and  for  pressure  sustaining  parts  such  as  air  chambers,  pump 
barrels,  valve  chambers,  steam  cylinders,  etc.,  the  tensile 
strength  should  be  as  high  as  from  22,000  to  25,000  Ibs.  per 
square  inch,  and  with  a  cross  breaking  strength  of  one  tenth 
as  befoie  mentioned. 

Good  steel  castings  have  become  a  common  and  commer- 
cial article  for  vaiious  parts  of  machinery,  and  are  acceptable 
for  cross  heads  and  other  parts  of  pumping  engines  where  for- 
merly forgings  only  were  used.  Such  castings  should  be  prop- 
erly annealed,  and  the  material  entering  into  them  would  be 
acceptable  when  the  specimens  showed  a  tensile  strength  of 
60,000  to  65,000  Ibs.  per  square  inch,  an  elongation  of  20  per 
cent  and  an  elastic  limit  of  30,000  Ibs.;  the  usual  test  speci- 
mens being  used  in  these  determinations. 


344  PUMPING  ENGINES 

Very  little  wrought  iron  aside  from  bolts  is  used  in  pumping 
engines,  and  the  usual  specimens  should  show  approximately 
45,000  Ibs.  tensile  strength,  25,000  Ibs.  elastic  limit,  and  20  per 
c  nt  elongation  in  8  inches. 

Composition  metal,  commonly  designated  brass,  varies 
considerably  in  the  vaiious  parts  and  as  used  by  various  build- 
ers. The  p.incipal  quantity  is  utilized  in  the  pump  valve 
seats  and  appurtenances,  and  should  be  made  of  new  metal 
mixed  at  the  time  of  melting,  for  the  best  work,  but  under 
ordinary  conditions  there  is  not  much  trouble  experienced 
with  the  metal  usually  employed. 

Bearing  metal,  or  tabbitt  metal  as  it  is  commonly  called, 
varies  a  good  deal  also,  but  bearing  metal  for  heavy  work 
should  be  made  of  copper,  tin,  and  antimony,  although,  like 
brass,  there  are  numerous  mixtures,  and  most  reputable  build- 
ers meet  this  requirement  in  acceptable  fashion. 

All  materials  for  the  machinery  should  be  subject  to  inspec- 
tion when  the  buyer  desires,  but  it  is  a  useless  expense  to  actually 
provide  for  such  testing  when  buying  a  pumping  engine,  as  the 
builder  will  of  course  add  all  contingencies  to  the  pi  ice  asked 
for  the  machinery.  Therefore  in  the  writer's  opinion  it  will  be 
better  to  secure  the  option  of  having  the  testing  done  when 
desired,  and  charge  the  cost  to  the  buyer  for  the  actual  work 
done  and  expense  involved  at  the  time  such  tests  may  really 
be  made. 


CHAPTER  XXVI 
DUTY  TESTS  OF   PUMPING  ENGINES 

THE  usual  and  practical  purpose  of  the  duty  test  of  a  pump- 
ing engine  is  to  find  out  whether  or  not  the  engine  con ti  acted 
for  and  installed,  is  capable  of  meeting  the  contract  guarantee 
of  efficiency  and  economy,  made  by  the  builder;  the  results  as 
ordinarily  expressed  in  foot  pounds  of  duty,  really  show  how 
many  pounds  of  water  the  engine  will  raise  one  foot  high  when 
it  consumes  cither  1,000  Ibs.  weight  of  steam,  or  1,000,000 
units  of  heat.  It  would  seem  as  though  scientific  research 
would  call  for  duty  tests,  so  as  to  determine  the  relation  between 
the  heat  expended  and  the  work  accomplished  by  the  machine ; 
but  the  trouble  of  this  is,  that  there  seems  to  be  no  one  to  pay 
the  bills  upon  a  large  enough  scale  to  be  of  much  use,  either 
theoretically  or  practically. 

And  therefore  the  slower  but  equally  certain  method  is  for 
close  hard  thinkers  and  observers  to  improve  from  time  to  time 
and  from  engine  to  engine,  in  the  pumping  engine  business. 
Then  by  noting  and  remembering  the  action  and  results  under 
different  and  various  conditions  of  pressures,  speeds,  capa- 
cities, etc.,  a  line  of  procedure  in  any  and  certain  cases  which 
arise,  is  finally  established.  After  some  years  of  experience, 
trials,  and  tribulations,  the  approximate  relation  between 
steam  economy  and  design  is  fairly  well  ascertained;  the  final 
results  seeming  to  show  that  purely  scientific  men  saw  the 
right  road  long  ago,  but  from  the  lack  of  opportunity  for  prac- 
tical application  could  not  travel  far  enough  and  could  not 
live  long  enough  to  find  out  exactly  what  kind  of  a  machine 
was  available  for  the  purpose  in  view. 

The  savants  who  many  years  ago  understood  a  good  deal 

345 


346  PUMPING  ENGINES 

about  the  strength  and  quality  of  materials,  and  the  possibilities 
of  heat,  were  somewhat  in  the  position  of  the  man  who  inquired 
of  the  gardener  at  a  certain  famous  educational  institution 
in  England,  how  he  produced  such  a  beautiful  lawn,  and  was 
answered : 

"You  must  first  level  and  prepare  the  soil  very  carefully, 
then  get  and  sow  the  very  best  seed  to  be  had,  and  then  mow 
and  trim  the  lawn  a  couple  of  hundred  years  or  more,  and  you 
will  get  the  results  you  are  looking  for." 

The  generation  of  steam  in  boilers  and  the  use  of  that  same 
steam  in  pumping  engines,  are  two  totally  different  opera- 
tions; independent,  and  distinct.  And  from  this  it  follows, 
that  the  boilers  are  not  responsible  for  the  steam  used  and 
wasted  by  the  engine,  and  that  the  engine  is  not  responsible 
for  the  cost  of  the  steam  produced  by  the  boilers.  But  in  the 
early  days  back  of  the  last  century,  when  the  pumping  of 
water  was  a  limited  industry,  before  men  had  looked  quite 
so  far  into  all  sides  of  the  question,  and  had  in  a  hard-headed, 
practical  way,  observed  only  the  coal  shoveled  into  the  boiler 
furnaces  and  the  amount  of  water  made  to  run  away  from 
the  top  of  the  mine  by  the  pump,  took  hold  apparently  of  only 
one  end  of  the  problem  in  real  earnest,  and  that  was  the  engine 
end  of  it.  Even  when  the  steam  pressure  was  raised  for  better 
economy  and  more  work,  it  was  on  account  of  the  engine,  and 
the  boilers  simply  had  to  meet  this  new  condition.  Therefore 
it  was  natural  enough  that  the  basis  of  100  Ibs.  of  coal  should 
finally  become  established  as  the  unit  of  what  was  consumed, 
to  be  charged  against  the  work  done  by  the  engine.  In  later 
years,  the  kind,  quality,  and  condition  of  the  fuel  used  for 
generating  steam,  arising  from  the  wide  application  of  pump- 
ing machinery,  took  the  engineer  far  afield  and  gave  him  all 
the  way  from  natural  gas,  oil,  tan  bark,  and  saw  dust,  to  the 
very  highest  qualities  of  anthracite  and  bituminous  coal,  and 
of  course  the  absurdity  of  talking  about  100  Ibs.  of  coal  as  a 
basis  for  duty  tests  became  apparent. 

After  a  while  it  became  to  be  generally  recognized  that  100 


DUTY  TESTS  OF  PUMPING  ENGINES  347 

Ibs.  of  good  Cumberland  coal  would  readily  evaporate  1,000 
Ibs.  of  water  into  steam,  and  so  the  unit  of  100  Ibs.  for  the 
consumption  of  fuel  was  based  upon  the  assumed  evaporation 
in  the  boilers  of  10  Ibs.  of  water  per  pound  of  coal;  the  actual 
record  of  coal  for  a  duty  test  being  ascertained  by  weighing 
the  feed  water  which  was  to  be  made  into  steam  in  the  boilers, 
and  dividing  the  amount  of  water  so  found  by  10,  the  result 
being  taken  as  the  weight  of  coal  which  would  be  consumed 
on  account  of  the  engine,  upon  the  basis  of  10  to  1  evaporation 
in  the  boilers.  It  did  not  require  very  much  time  after  going 
so  far  to  perceive  that  a  still  shorter  road  to  a  statement  of 
the  results  obtained,  would  be  to  base  the  duty  developed 
directly  upon  the  unit  of  1,000  Ibs.  weight  of  steam  delivered 
to  the  engine.  The  use  of  this  basis,  separating,  as  it  does, 
the  performance  of  the  boilers  .from  that  of  the  engine,  is  now 
very  much  used,  although  still  another  basis  has  been  brought 
forward,  and  that  is  the  million  heat  unit  basis,  which  is  simply 
another  way  of  using  the  old  coal  basis  of  100  Ibs.  by  assuming 
that  good  boiler  work  consists  in  utilizing  10,000  heat  units 
per  pound  of  coal  by  the  boilers,  or  1,000,000  heat  units  per 
100  Ibs.  of  coal.  The  method  of  testing  a  pumping  engine  upon 
the  basis  of  work  done  by  the  main  pumps,  per  1,000  Ibs.  of 
dry  steam  supplied  to  the  steam  cylinders,  jackets,  reheaters, 
etc.,  appeals  to  the  writer  as  the  simplest  and  most  satisfactory, 
and  also  the  method  most  in  line  with  the  actual  performance 
of  making  and  using  of  steam  for  the  pumping  of  water.  The 
heat  unit  basis  is,  perhaps,  strictly  speaking,  the  more  scien- 
tific, and  a  method  which  builders  of  pumping  machinery  will 
want  to  know  the  results  of.  But,  after  all,  the  steam  must 
be  made  at  some  certain  cost  entirely  independent  of  either 
method  of  testing,  and  the  feed  water  must  be  weighed  in  either 
case  so  as  to  know  how  much  either  of  steam  or  of  heat  goes 
into  the  cylinders  and  appurtenances  of  the  engine. 

First,  taking  up  the  1,000  Ibs.  of  steam  basis,  reckoned  from 
the  weight  of  feed  water;  when  the  contract  requirements 
for  duty  are  based  upon  the  quantity  of  steam  sent  from  the 


348  DUMPING  ENGINES 

boilers  and  used  in  the  engine,  great  care  must  be  taken  to 
accurately  determine  this  amount;  all  connections  between 
the  boilers  which  supply  steam  to  the  engine,  and  other  boilers 
in  the  station,  must  be  either  broken  or  closed  with  blank  flanges. 
The  water  used  as  feed  water  for  the  boilers  supplying  steam 
for  the  test,  may  be  drawn  from  the  force  main  or  other  suit- 
able source,  and  discharged  into  weighing  tanks  or  barrels 
placed  upon  platform  scales,  the  scales  having  been  tested 
by  some  sort  of  official  weights;  and  from  the  weighing  barrels 
the  water  is  discharged  into  a  tank  or  barrel  from  which  the 
supply  for  the  boilers  is  taken.  Provisions  must  be  made 
for  either  obtaining  the  weight  of  the  drainage  from  con- 
densed steam  within  the  main  steam  pipe,  or  for  returning 
this  water  directly  to  the  boilers;  but  the  drainage  of  con- 
densed steam  from  the  steam  jackets  and  receiver  coils  must 
be  allowed  to  escape  as  part  of  the  steam  consumed  by  the 
engine. 

During  the  test,  all  steam  used  for  mechanical  stokers,  and 
for  any  other  purposes  not  fairly  chargeable  against  the  work 
done  by  the  main  engine,  must  be  taken  from  a  boiler  separate 
from  the  steam  supply  for  the  main  engine,  and  this  brings  in 
the  question  of  feed  pump  supply  where  the  boilers  are  supplied 
with  water  by  a  pump  independent  of  the  main  engine.  The 
complete  pumping  engine  must  feed  its  own  boilers,  and  this  can 
be  readily  and  often  is  done  by  an  attached  feed  pump  on  the 
main  engine ;  and  so  this  amount  of  work,  amounting  to  about 
one  quarter  of  one  per  cent  of  the  total  power,  is  in  such  case 
provided  by  the  pumping  engine  itself.  When  an  independent 
steam  pump  is  used,  there  would  be  a  consumption  of  steam  in 
proportion  to  the  work  of  feeding  the  boilers,  very  much  in 
excess  of  what  would  be  required  by  the  main  engine  for  the 
same  amount  of  work  with  an  attached  feed  pump.  This  use 
of  steam  by  an  independent  pump  would  unfairly  and  adversely 
affect  the  duty  record  of  a  pumping  engine,  so  a  compromise  is 
in  order ;  and  a  reasonable  one  is  to  charge  the  main  engine  with 
the  wo"  k  of  feeding  the  boilers  by  deducting  the  foot  pounds 


DUTY  TESTS  OF  PUMPING  ENGINES  349 

represented  by  such  an  amount  of  work,  from  the  total  woik 
shown  by  the  main  engine,  before  dividing  the  total  foot 
pounds  for  the  duty  results.  The  writer  distinctly  remem'  ers 
such  a  controversy  some  years  ago  when  testing  a  pumping 
engine  in  conjunction  with  Professor  David  M.  Greene.  The 
professor  represented  the  city  buying  the  engine,  and  the  writer 
repiesented  the  builders;  and  in  summing  up  the  articles,  so 
to  speak,  just  before  the  test  was  commenced,  the  absence 
of  an  attached  feed  pump  became  known.  The  city's  rep- 
resentative and  the  builders'  representative  promptly  began 
a  lively  debate,  and  at  one  time  it  looked  as  though  the  third 
man  provided  for  by  the  contract  in  case  of  dispute  would 
have  to  be  sent  for. 

The  city's  man  said  that  the  engine  was  not  complete  unless 
it  fed  its  own  boilers,  and  in  the  absence  of  its  own  feeding 
apparatus  the  engine  must  take  the  consequences.  The  build- 
er's man  said  that  the  duty  was  to  be  based  upon  the  steam 
consumed  by  the  engine  itself  and  not  by  a  steam  devouring 
direct  acting  steam  pump  requiring  200  Ibs.  of  steam  per  horse 
power  hour.  Finally  the  suggestion  was  made,  — modesty  for- 
bids recording  by  whom,  —  that  the  foot  pounds  found  by 
multiplying  the  weight  of  the  feed  water,  by  the  head  in  feet 
represented  by  the  boiler  steam  piessuie,  be  deducted  from 
the  total  work  of  the  main  pumping  engine  before  the  final 
calculation  for  duty  was  made,  and  then  the  steam  for  the  inde- 
pendent steam  pump  to  be  taken  from  a  boiler  separate  from 
those  supplying  the  main  engine. 

After  due  consideration,  and  a  proper  amount  of  suspicion 
displayed  by  the  other  man,  this  was  agreed  upon  and  then 
the  clouds  disappeared.  The  principle  involved  in  this  adjust- 
ment is  that  a  pumping  engine  under  this  sort  of  a  test  should 
do  certain  things  that  fairly  belong  to  its  work,  and  if  it  is  not 
fitted  up  to  do  all  of  the  proper  auxiliary  work,  then  have  it 
done  in  some  convenient  way,  and  charge  such  work  actually 
done  to  the  main  engine,  but  do  not  handicap  the  machine  by 
more  wasteful  methods  than  it  employs  itself.  The  equity 


350  PUMPING  ENGINES 

of  the  matter  is  that  the  buyer  can  get  the  benefit  of  econo- 
mical attached  auxiliaries  by  paying  for  them,  and  the  original 
price  for  the  engine  would  have  been  higher  if  the  auxiliaries 
had  been  attached  to  the  main  engine  in  the  first  place. 

However,  this  rule  would  not  apply  where  an  independent 
condensing  apparatus  is  used  in  connection  with  a  pumping 
engine,  as  the  driving  of  the  air  pump  is  too  much  a  part  of 
the  work  of  the  main  engine  to  be  ignored.  Too  large  a  share 
of  the  economy  of  the  machine  comes  from  the  use  of  a  vacuum, 
to  omit  the  steam  consumed  by  the  independent  air  pump 
from  that  charged  against  the  total  work  done;  but  of  course 
in  the  case  of  the  independent  air  pump  if  the  steam  is  charged 
the  main  engine  must  be  credited  with  the  work  represented 
by  the  operation  of  such  an  air  pump,  as  when  the  air  pump 
is  attached  to  the  main  engine  the  work  done  by  the  air  pump 
is  included  in  its  own. 

It  is  fair  and  proper  to  determine  the  leakage  from  the  boilers 
and  piping  under  pressure  during  the  engine  test,  and  deduct 
the  amount  found  from  the  steam  consumption,  as  it  is  plain 
that  water  fed  to  boilers  for  steam  making  cannot  be  fairly 
charged  to  the  engine  if  a  part  of  such  water  gets  away  before 
it  is  received  by  the  engine  as  steam;  and  the  records  show 
that  no  boiler  and  its  pipings  are  absolutely  steam  tight.  The 
lowest  record  of  leakage  of  boilers  and  pipes  known  to  the 
writer  is  sixteen  hundredths  of  one  per  cent;  another  low  record 
is  seventy-four  hundredths  of  one  per  cent;  and  there  are  plenty 
of  boi  ers  and  pip  ng  easily  as  high  as  two  per  cent  and  more. 
In  the  absence  of  an  actual  test  for  such  leakage,  it  is  no  more 
than  fair  to  allow,  say,  one  per  cent  for  boiler  and  steam  pipe 
leakage,  when  the  duty  of  the  engine  is  desired  accurately  and 
in  the  absence  of  prohibition  on  this  point  in  the  contract. 

If  the  boilers  are  to  be  measured  for  loss  before  the  engine 
test  is  commenced,  as  good  a  way  as  any  is  to  measure  the 
amount  which  the  water  will  drop  in  the  glass  gauges  by  draw- 
ing from  the  boilers  certain  known  weights  of  water,  and  then 
note  the  difference  in  water  level  in  the  glasses  corresponding 


DUTY  TESTS  OF  PUMPING  ENGINES  351 

to  such  quantities  withdrawn.  Then  king  these  readings 
of  water  levels  to  an  average  basis  of  one  inch  and  correct  if 
necessary  for  difference  in  temperatures;  and  this  will  show 
that  for  each  inch  and  fraction  of  an  inch  of  change  in  water 
level  in  each  boiler,  a  certain  weight  of  water  would  have  to 
be  accounted  for,  either  above  or  below  any  certain  fixed  mark, 
for  a  range  within  the  ordinary  uses  of  the  boilers. 

After  so  fixing  the  rate  of  change  in  level  and  weight  in  the 
boilers  to  be  used  for  the  engine  test,  a  test  for  leakage  should 
be  made  for  these  boilers,  by  placing  them  under  the  working 
pressure  for,  say,  ten  hours,  and  noting  the  loss  in  water  level 
as  indicated  by  the  drop  of  the  water  in  the  glass  gauges. 
Any  steam  condensed  within  the  main  steam  and  connections 
during  this  test  can  be  sent  through  a  pipe  coil  surrounded 
by  cold  water  and  then  weighed,  the  amount  so  found  to  be 
deducted  from  the  amount  noted  as  disappearing  from  the 
boilers  in  the  glass  gauges. 

A  test  should  also  be  made  to  ascertain  how  much  steam 
would  be  lost  from  the  main  steam  pipe  by  the  operation  of  the 
calorimeter,  it  being  necessary  to  blow  a  certain  amount  of 
steam  from  the  outlet  of  the  calor'meter  to  ascertain  the  per- 
centage of  moisture  in  the  steam  going  into  the  engine,  where 
under  the  contract  the  engine  is  entitled  to  the  credit  of  such 
percentage  of  water  contained  in  the  steam,  and  also  a  credit 
for  the  amount  of  steam  wasted  in  operating  the  calorimeter. 

Then,  in  a  1,000  pound  feed  water  test,  the  net  dry  saturated 
steam  used  by  the  engine  during  the  duty  test  would  be  ascer- 
tained by  deducting  f;om  the  gross  weight  of  feed  water  sent 
to  the  boilers,  including  what  amount  may  be  needed  at  the 
close  of  the  test,  if  any,  to  make  up  the  correct  boiler  level  in 
the  gauge  glasses;  the  leakage  ascertained;  calorimeter  waste; 
any  other  observed  leakage  before  the  steam  reaches  the  main 
throttle  valve;  and  the  amount  of  water  represented  by  th3 
entrainrnent  within  the  steam  passing  the  engine  throttle  valve. 

Sometimes  in  competition  pumping  engine  builders  will 
try  to  outdo  each  other  in  the  line  of  guaranteeing  high  duties, 


352  PUMPING  ENGINES 

and  then  bringing  forward  the  argument  that  a  higher  duty 
at  a  higher  price  is  a  better  engine  than  the  reverse  proposition; 
•and  sometimes  the  engines  are  guaranteed  so  high  that  it 
requires  all  sorts  of  expert  manipulation  to  meet  the  contract 
when  the  day  of  testing  the  engine  at  length  rolls  around.  In 
such  cases  the  entrainment  of  water  in  the  steam  is  eageily 
looked  after  and  very  sharply  too,  for  it  is  a  direct  credit,  and 
the  larger  it  can  be  made,  the  more  the  steam  divisor  is  reduced 
in  the  final  calculation,  which  tells  the  tale  of  success  or  failure 
in  the  attempt  to  make  the  required  duty.  The  story  is  told 
of  a  representative  of  one  of  the  large  makers  of  pumping 
machinery,  who  must  have  been  a  real  expert,  by  the  way, 
who  perceived  that  the  results  were  alarmingly  close,  and,  as 
he  had  exhausted  every  allowance  he  was  entitled  to,  wiped 
the  perspiration  from  the  faces  of  the  firemen  and  running 
engineers,  and  by  sustaining  the  claim  that  this  should  be 
added  to  the  entrainment  because  its  presence  was  due  to  the 
heat  of  the  boilers,  just  managed  to  pull  through  on  the  duty 
requirements. 

If  the  1,000  Ibs.  of  steam  test  is  upon  the  basis  of  dry  satu- 
rated steam,  then  any  superheat  in  the  steam  used  must  be 
charged  against  the  engine,  by  adding  to  the  net  weight  of 
dry  saturated  steam  ascertained  in  the  manner  already  given, 
the  weight  of  steam  that  could  be  made  by  the  heat  units 
shown  by  the  amount  of  superheat  observed.  This  would 
be  done  by  multiplying  the  degrees  of  superheat  by  0.48,  which 
will  give  the  units  of  heat  in  one  pound  weight  of  the  super- 
heated steam  over  and  above  the  regular  amount  of  heat  due 
to  dry  saturated  steam ;  and  this  multiplied  by  the  net  weight 
of  steam  used,  and  then  divided  by  the  difference  between  the 
total  heat  units  in  steam  at  the  observed  pressure  and  the 
heat  units  in  the  feed  water  where  it  enters  the  boilers,  will 
give  the  extra  pounds  weight  of  steam  to  be  charged  against 
the  engine  in  addition  to  that  found  in  the  usual  way. 

When  steam  shows  more  moisture  than  it  is  entitled  to 
according  to  the  pressure  and  temperature  of  dry  saturated 


DUTY  TESTS  OF  PUMPING  ENGINES  353 

steam  given  in  a  proper  steam  table,  it  is  said  to  contain 
entrained  water;  and  therefore  if  the  contract  duty  is  based 
upon  dry  saturated  steam,  a  correction  must  be  made  in  favor 
of  the  engine,  because  there  is  more  weight  in  the  steam  charged 
against  it  than  dry  saturated  steam  can  show.  As  the  latent 
heat  in  the  steam  is  the  same  percentage  short  as  the  percent- 
age of  moisture,  the  correction  can  be  made  by  multiplying 
the  latent  units  of  heat  from  the  steam  table  according  to  the 
pressure  observed,  by  this  percentage  expiessed  in  decimals, 
and  the  result  will  show  how  many  heat  units  must  be  deducted 
from  the  total  heat  in  the  steam  to  give  the  actual  heat 
units  in  a  pound  of  the  moist  steam.  Then  this  result  divided 
by  the  total  heat  given  in  the  table  will  show  what  percentage 
of  a  pound  of  dry  saturated  steam  the  actual  amount  of  heat 
will  make.  This  latter  result  subtracted  from  one  (1)  will 
indicate  the  percentage  to  be  deducted  from  the  net  weight 
of  steam  obtained  during  the  test  already  referred  to. 

Second,  taking  up  the  million  heat  units  basis,  it  will  per- 
haps be  well  to  remark  that  a  heat  unit,  or  a  unit  of  heat,  com- 
monly known  as  a  British  Thermal  Unit,  is  the  amount  of  heat 
which  will  raise  the  temperature  of  one  pound  of  fresh  water 
one  degree,  on  the  scale  of  the  Fahrenheit  thermometer,  that 
is  the  ordinary  thermometer  we  are  used  to  seeing  every  day 
(water  at  a  temperature  of  39  degrees). 

When  the  requirement  for  duty  is  calculated  upon  the  heat 
unit  basis,  it  is  made  to  cover  all  of  the  heat  used  by  the 
main  engine  and  its  appurtenances  and  auxiliaries;  including 
the  steam  cylinders  of  the  main  engine,  steam  jackets,  reheat- 
ing coils,  steam  feed  pump  if  such  is  used,  the  independent  air 
pump  if  one  is  used  and  driven  by  steam,  and  every  other  appur- 
tenance and  appliance  or  apparatus  using  steam,  and  necessary 
to  the  operation  of  the  pumping  engine.  In  the  steam  supply 
for  the  engine,  allowance  must  be  made  for  moisture  or  for 
superheat  as  the  case  may  be,  as  the  heat  unit  basis  demands 
that  the  real  total  heat  of  the  steam  be  determined. 

The  heat  units  consumed  by  the  engine  is  the  difference 


354  PUMPING  ENGINES 

between  the  heat  units  sent  into  the  boiler  in  the  feed  water, 
and  the  heat  units  taken  out  of  the  boiler  in  the  steam  which 
the  engine  uses.  This  difference  is  supplied  by  the  burning 
fuel,  and  it  is  the  total  amount  of  heat  given  up  by  the  fuel 
for  steam,  legardless  of  the  quality  of  the  fuel  itself,  and  which 
is  divided  into  blocks  of  1,000,000  heat  units  each.  From 
this  the  woik  done  by  the  engine  per  million  heat  units  is  found 
by  dividing  the  total  work  done  by  the  engine  in  foot  pounds, 
by  the  total  number  of  heat  units  shown  to  have  been  sup- 
plied which  will  give  the  foot  pounds  of  duty  for  each  unit, 
and  this  number  multiplied  by  1,000,000  reduces  the  result 
to  the  basis  desired,  which  is  the  number  of  foot  pounds  of 
work  done  by  the  engine  for  each  1,000,000  British  thermal 
units  consumed  by  the  engine  and  its  appurtenances. 

If  any  heat  is  obtained  from  the  boiler  smoke  flue  or  con- 
nection by  the  use  of  a  coil  or  similar  device  connected  with 
any  pait  of  the  engine,  so  as  to  give  the  engine  the  advantage 
of  heat  escaping  fiom  the  boilers,  this  heat  must  be  added 
to  that  which  is  indicated  by  the  steam  consumed;  because 
it  will  be  heat  from  the  combustion  of  the  fuel  just  the  same 
as  though  it  was  received  by  the  engine  in  the  form  of  steam; 
also,  heat  obtained  and  absorbed  by  the  feed  water  from 
coils  or  heaters  in  the  boiler  flues  and  connections  is  to  be 
treated  as  an  addition  to  that  obtained  over  and  above  the 
heat  put  into  the  feed  water  by  the  engine  itself  and  its  appur- 
tenances. In  fact,  no  allowances  are  to  be  deducted  from 
the  heat  charged  against  the  engine,  which  comes  from  any 
source  excepting  the  engine  and  its  appurtenances. 

As  the  heat  unit  basis  depends  upon  the  actual  amount 
of  heat  in  the  steam  used,  the  total  heat  of  the  steam  found 
in  a  steam  table  is  corrected  for  entrained  water,  or  moisture, 
and  also  for  superheat.  Steam  contains  moisture  because 
there  is  not  enough  heat  present  in  the  steam  to  make  it  dry; 
and  as  the  sensible  temperature,  or  the  temperature  shown 
by  the  thermometer,  is  always  in  evidence  according  to  the 
pressure,  it  follows  that  the  shortage  is  in  the  latent  heat,  or 


DUTY  TESTS  OF  PUMPING  ENGINES  355 

that  portion  of  the  heat  in  the  steam  which  the  thermometer 
does  not  show,  but  which  is  absoibed  at  the  time  of  evapora- 
tion in  the  boilers.  Therefore,  if  there  is  one  per  cent  of  mois- 
tu:e  or  entrained  water  shown  to  exist  in  the  steam,  the  latent 
heat  is  one  per  cent  short;  so  the  units  of  heat  given  as  latent 
in  the  steam  table  are  to  be  discounted  one  per  cent,  and  the 
total  heat  in  the  steam  is  to  be  taken  at  one  per  cent  of  the 
latent  heat  short  of  the  total  amount  given  in  the  steam  table, 
per  pound  weight. 

Another  way  for  determining  the  amount  of  heat  consumed 
by  the  engine  and  its  appurtenances,  when  there  is  moistuie 
in  the  steam,  which  will  give  the  same  result  as  that  already 
given,  and  therefore  furnish  a  check  on  the  first  method,  is  as 
follows : 

After  the  correct  weight  of  the  feed  water  has  been  found, 
subtract  from  this  weight  the  percentage  of  moisture  in  pounds, 
shown  to  exist  in  the  steam;  the  weight  of  the  moisture  or 
entrained  water  is  found  by  multiplying  the  correct  weight 
of  the  feed  water  by  the  percentage  of  moisture  expressed 
in  decimals.  The  remainder  given  by  this  subtraction  will 
be  the  weight  of  dry  saturated  steam  possible  to  make  with 
the  heat  present. 

Next  multiply  this  weight  of  dry  saturated  steam  by  the 
total  heat  units  per  pound  found  in  the  steam  table;  and  then 
multiply  the  weight  shown  by  the  percentage  of  moisture, 
by  the  units  of  heat  per  pound  of  water  at  the  temperature 
due  to  the  pressu.e  observed.  The  sum  of  these  will  be  the 
total  heat  actually  supplied  to  the  engine,  which  must  be 
corrected  for  duty  calculations  by  subtracting  the  units  of 
heat  sent  into  the  boilers  by  the  various  supplies  of  feed  water. 

If  the  steam  is  superheated,  it  indicates  that  whatever  num- 
ber of  degrees  the  steam  is  shown  to  be  hotter  than  the  tem- 
perature called  for  by  the  steam  table  due  to  the  observed 
pressure,  there  is  present  in  the  steam  0.48  of  a  unit  of  heat 
for  each  degree  superheat  above  the  normal  temperature  of 
steam  called  for  by  the  table.  The  heat  to  be  added  to  the 


356  PUMPING  ENGINES 

account  against  the  engine  by  reason  of  superheat,  is  found 
by  multiplying  the  number  of  degrees  superheat  by  0.48  and 
then  multiplying  this  product  by  the  net  weight  of  the  feed 
water  shown  to  have  been  used  for  steam. 

When  the  feed  water  is  combined  from  all  sources  about 
the  engine  and  sent  to  the  boilers  as  one  body,  at  one  average 
temperature,  this  temperature  is  to  be  taken  at  some  conven- 
ient place  as  near  to  the  boilers  as  practicable.  But  when 
there  are  several  separate  temperatures  of  feed  water  sent 
by  different  pipes  so  as  not  to  conveniently  combine  together, 
as,  for  example,  one  from  the  hot  well,  one  from  the  jacket 
condensation,  and  from  reheater  coils,  or  other  sources  at  dif- 
ferent temperatures,  they  are  to  be  treated  separately  on 
account  of  the  heat  units  due  to  the  various  temperatures 
to  be  compared  with  the  steam  going  to  the  engine. 

Then  the  total  number  of  heat  units,  or "  British  thermal 
units,  consumed  by  the  engine  and  its  appurtenances  is  taken 
f.om  the  weight  of  the  water  sent  into  the  boileis  by  the  main 
feed  pump;  the  weight  of  the  water  sent  in  from  the  steam 
jacket  drainage ;  the  weight  of  the  water  sent  in  from  the  reheater 
coil  drainage;  and  the  weight  of  any  other  water  sent  to  the 
boilers  at  a  different  temperature  from  any  of  the  other  sup- 
plies. These  different  weights  are  to  be  multiplied  by  the 
total  heat  in  the  steam,  calculated  from  the  different  tem- 
peratures of  the  different  sources  of  feed  water;  and  the  result 
obtained  in  heat  units  added,  together  for  the  total  heat  units 
consumed. 

Even  under  the  heat  unit  method  for  calculating  the  duty 
of  a  pumping  engine,  the  contractor  sometimes  guarantees 
a  rather  high  duty,  which  of  course  has  to  be  shown  somehow 
or  other  by  the  expert,  or  at  least  earnest  endeavors  to  show 
that  everything  is  all  right  have  to  be  put  forth  now  and  again. 
Another  story  is  told  of  an  incident  which  happened  in  con- 
nection with  one  of  these  heat  unit  duty  tests,  also  involving 
one  of  the  larger  manufacturers;  in  fact,  the  large  buildeis  are 
the  ones  who  have  such  blight  and  attentive  representatives. 


I 
DUTY  TESTS  OF  PUMPING  ENGINES  357 

It  seems  that  this  test  was  about  half  finished  and  it  had  become 
apparent  that  the  guarantee  was  a  very  high  one  for  this  par- 
ticular engine,  the  chances  evidently  being  against  the  machine. 
There  was  a  cistern  outside  of  the  boiler  room,  and  one  of  the 
firemen  just  going  off  watch  accidentally  fell  into  it,  but  suf- 
fered no  damage  beyond  the  thorough  soaking  of  his  clothes. 
The  weather  being  rather  raw  he  feared  taking  cold,  so  retu:  ned 
to  the  boiler  room  and  backed  up  near  to  the  hot  front  of  one 
of  the  boilers  making  steam  for  the  test;  but  just  at  that  time 
the  expert  came  into  the  boiler  room  to  look  after  the  water 
level,  and  taking  in  the  situation  at  a  glance,  ordered  the  wet 
fireman  away  from  the  boiler  front,  telling  him  in  no  stinted 
terms  that  this  test  was  a  heat  unit  test,  and  there  were  no 
heat  units  to  be  spared  for  drying  clothes  or  for  any  purpose 
whatever  outside  of  running  the  engine. 

Having  provided  for  finding  out  the  steam  or  heat  consump- 
tion duiing  the  duty  test,  the  plunger  load,  or  the  work  done 
by  the  pumping  engine,  comes  in  for  equally  careful  attention. 
The  measuring  of  the  work  done  carries  with  it  the  deteimina- 
tion  of  the  quantity  of  water  delivered  into  the  force  main  of 
the  pump,  and  although  several  and  various  ways  have  been 
advocated  and  tried  from  time  to  time,  including  weir  meas- 
urements, Venturi  meter  tubes,  nozzles  of  known  delivery 
under  certain  conditions,  etc.,  it  is  becoming  pretty  geneially 
conceded  by  disinterested  people  looking  for  the  facts,  that 
in  a  properly  designed  and  constructed  displacement  pump, 
the  plunger  displacement  will  give  closer  results  in  a  matter 
where  perfection  is  impossible,  than  any  other  method.  In 
fact,  aside  f i  om  the  slight  leakage  and  loss  inherent  in  the  very 
best  of  pumps,  the  pump  itself  is  a  perfect  meter;  and  there 
are  loss  and  error  in  all  means  for  determining  quantities  of 
water  outside  of  the  pump.  There  is  another  advantage  in  the 
use  of  the  pump  itself  for  measuring,  and  that  is,  that  the  en  or, 
whatever  it  may  be,  is  always  on  the  same  side  of  the  calcu- 
lation, whereas  in  about  everything  else  used  for  measuring 
the  error  may  be  on  either  side  of  the  account,  especially  so 


358  PUMPING  ENGINES 

with  weirs,  and  a  weir  would  make  itself  ridiculous  and  every 
one  connected  with  it  as  well,  if  it  indicated  more  water  by 
having  too  high  a  velocity  of  approach  than  the  plungers  could 
displace.  Also,  experiments  tried  by  the  writer  have  at  dif- 
ferent times  demonstrated  that  the  record  of  a  measuring 
instrument  placed  in  connection  with  the  suction  flow  will  vary 
at  all  times,  with  a  record  of  the  same  instrument  placed  in 
connection  with  the  discharge  flow,  and  vary  greatly  sometimes. 
The  slight  leakage  around  outside  packed  plungers  can  be 
measured  down  to  a  very  fine  point  and  the  correction  made 
for  readings  before  and  after  the  water  has  been  pumped. 
Allowing,  then,  such  corrections,  the  quantity  flowing  through 
the  suction  ought  to  be  the  same  as  in  the  delivery  if  the 
quantity  is  really  and  accurately  measured,  or  at  least  correct 
within  the  limits  of  trained  observation. 

Another  experience  is  also  recalled,  where  there  was  an  oppor- 
tunity of  comparing  the  delivery  of  a  large  and  perfectly  con- 
structed weir  according  to  the  Francis  formula,  and  two  Venturi 
meters.  Very  great  precautions  were  taken  in  making  the 
comparisons,  and  considering  the  amount  of  care  and  precision 
given  to  the  work,  there  is  no  reason  to  doubt  that  every  possible 
error  in  manipulation  and  observation  was  avoided.  There 
was  a  disagreement  of  about  2  per  cent  between  these  two 
methods  of  measuring  water,  and  this  disagreement  is  more 
than  any  well  regulated  pumping  engine  will  show  under 
good  conditions,  with  as  clear  water  as  in  the  abpve  mentioned 
test,  and  with  outside  packed  plungers.  No  reflection  is 
intended  upon  either  of  the  above  methods  or  against  any 
other  method;  the  desire  is  only  to  get  at  the  facts  as  closely 
as  possible ;  and  where  weirs  or  meters  can  be  used  in  conjunc- 
tion with  plunger  displacement,  it  is  by  all  means  the  thing 
to  do  in  endeavoring  to  arrive  at  the  facts. 

The  work  actually  done  by  the  steam  engine  portion  of  the 
machine  where  the  plungers  are  moved  against  a  water  press- 
ure or  load,  is  just  the  same  as  though  none  of  the  water  escaped 
going  into  the  force  main.  The  water  that  escapes  past  the 


I 
DUTY  TESTS  OF  PUMPING  ENGINES  359 

plungers  or  through  the  valves,  goes  out  under  the  working 
pressure,  and  the  power  developing  end  of  the  engine  knows 
no  difference  as  to  the  means  and  way  of  escape  in  quantities 
up  to  the  ordinary  losses  in  such  machinery.  It  is  not  diffi- 
cult to  determine  very  closely  the  amount  of  loss  or  leakage, 
if  in  the  interest  of  the  buyer  this  is  desired;  but  as  such  losses 
in  a  well  made  pump  in  good  order  are  very  small,  there  is 
really  very  little  use  in  spending  money  beyond  what  is  de- 
manded by  proper  surroundings  for  the  engine.  If  a  pump 
is  well  designed  and  made,  with  the  size,  number,  and  lift  of 
its  water  valves  in  good  proportion  to  the  capacity,  pressure, 
and  speed,  for  clear  fiesh  water,  the  builder  should  not  be  held 
responsible  as  to  the  amount  of  water  it  will  actually  pump 
under  bad  conditions ;  and  it  will  be  to  the  interest  of  the  buyer 
to  have  his  conditions  brought  as  nearly  to  the  clear  water 
basis  as  can  possibly  be  done.  The  pump  is  not  responsible 
for  chips,  rubbish,  fish,  and  other  things  not  meant  for  a  pump 
to  handle,  and  the  buyer  and  user  is  greatly  interested  in  seeing 
that  the  pump  well  is  properly  screened  and  kept  clear  of  all 
substances  not  intended  to  be  in  there.  So,  according  to  the 
writer's  views,  the  most  practicable  way  to  meet  this  question 
is  to  calculate  the  plunger  capacity  5  per  cent  above  the  nor- 
mal contract  capacity  in  order  that  the  buyer  will  be  very 
certain  to  get  the  full  amount  of  water  figured  upon  for  actual 
use,  or  waste,  and  then  make  the  duty  test  squarely  upon  the 
plunger  displacement.  If  all  makers  bid  upon  this  basis  under 
competent  specifications,  the  buyer  will  get  just  about  what 
he  is  looking  for,  so  far  as  capacity  is  concerned;  the  duty 
shown  upon  test  by  plunger  displacement  will  be  a  good  con- 
ventional guide  for  future  operations,  and  with  a  proper  dis- 
placement pump,  will  under  good  conditions  be  as  close  to  the 
facts  as  any  other  practical  method  will  carry  him. 

In  finding  the  plunger  load,  a  mercury  column  is  decidedly 
the  best  and  most  accurate  way,  and  it  is  worth  while  taking 
some  trouble  to  fit  one  up  for  a  test.  Tested  water  pressure 
gauges,  compared  with  some  permanently  constructed  mer- 


360  PUMPING  ENGINES 

cury  column,  where  one  is  available;  or  with  some  form  of  dead 
weight  apparatus,  as,  for  example,  the  Crosby  dead  weight 
testing  machine,  will  answer  very  well  for  leading  the  load, 
if  it  be  impracticable  to  set  up  a  temporary  mercury  column 
in  connection  with  the  engine  being  tested.  In  most  pumping 
stations  there  is  height  enough  from  the  basement  floor  to  a 
moderate  distance  above  the  main  engine  room  floor,  to  place 
a  mercury  column  which  can  be  well  made  of  iron  pipe  most 
of  the  way,  and  with  several  feet  of  glass  tube  near  the  upper 
end;  but  the  mercury  should  not  come  in  contact  with  brass. 
A  very  perfect  reading  scale  can  be  easily  attached  to  a  board 
near  where  the  mercury  level  would  naturally  come,  when 
the  tube  is  filled  up  with  the  mercury  to  the  working  load. 

A  bench  mark  can  be  established  by  means  of  a  surveying 
instrument,  and  to  this  bench  mark  all  vertical  measurements 
can  be  referred.  The  elevation  of  the  water  in  the  pump 
well  can  be  read  from  a  graduated  board  set  to  correspond 
with  the  established  bench  mark,  in  such  a  manner  that  the 
reading  of  the  mercury  column  or  pressure  gauge,  whichever 
is  used,  can  be  added  to  the  reading  of  the  well  gauge,  and  so 
give  the  total  head  in  feet  against  which  the  plungers  operate. 
But  there  are  generally  certain  corrections  for  temperature, 
disturbance  of  water  levels,  pressures,  etc.,  etc.,  to  be  made, 
for  finding  the  actual  working  head  under  the  conditions  found 
at  different  pumping  stations. 

The  diameter  and  stroke  of  the  plungers  submitted  in  a 
bid,  and  shown  in  the  plans  for  a  pumping  engine,  should  be 
verified  before  positive  statements  about  a  duty  test  are  made. 
These  measurements  should  be  made  by  instruments  of  pre- 
cision, such  as  micrometers,  steel  scales  and  tape  lines,  from 
well  recognized  makers.  The  actual  dimensions  of  the  work 
as  furnished  in  the  engine  is  generally  found  to  vary  some- 
what fiom  specifications,  even  when  coming  from  the  best 
Concerns,  although,  to  the  credit  of  the  builders,  generally  vary- 
ing in  going  a  little  over  the  full  measure;  as,  for  example,  in 
two  cases  known  to  the  writer,  of  recent  occurrence,  one  a 


DUTY  TESTS  OF  PUMPING  ENGINES  361 

triple  and  one  a  cross  compound  pumping  engine.  The 
plungers  of  the  triple  machine  were  high  pressure  28.253,  and 
intermediate  pressure  28.253,  and  low  pressure,  28.259  inches 
diameter;  the  size  called  for  in  the  contract  was  28.25  inches, 
for  all.  The  stroke  for  high  pressure  60.05,  and  intermediate 
pressure  60.01,  and  low  pressure  60.03  inches  respectively; 
the  stioke  called  for  in  the  contract  was  60  inches,  In  the 
cross  compound,  the  plungers  were,  high  pressure  18.263  and 
low  pressure  18.279  inches  diameter,  where  18.25  inches  dia- 
meter was  called  for  in  the  contract  for  both  plungers;  the 
stroke  of  both  plungers  was  48.125  inches  where  48  inches 
was  called  for  in  the  contract.  These  differences  are  very 
fine,  but  they  show  that  these  engines  would  meet  the  dis- 
placement capacity  without  any  doubt  whatever. 

The  capacity  of  the  plungers  per  revolution  of  the  engine, 
in  cubic  feet,  having  been  established  from  the  diameter  and 
stroke  found  by  the  measurements,  the  weight  of  a  cubic  foot 
of  water  must  be  decided  upon,  and  from  this  the  weight  of 
water  per  revolution  is  readily  obtained.  The  number  of  U.  S. 
gallons  per  revolution  is  obtained  by  multiplying  the  cubic 
feet  by  7.4805,  the  number  of  U.  S.  gallons  of  231  cubic  inches 
each,  contained  in  one  cubic  foot  of  1,728  cubic  inches.  In 
ascertaining  the  weight  of  a  cubic  foot  of  water  in  the  pump 
well,  the  temperature  must  be  known,  and  the  weight  corre- 
sponding to  the  observed  temperature  may  just  as  well  be  taken 
from  some  well  recognized  table  of  weights  of  water  at  different 
temperatures,  as  it  is  impossible  to  get  any  vessel  measured 
closely  enough  for  a  cubic  foot  or  a  cubic  inch,  or  any  other 
capacity,  for  any  two,  or  any  other  number  of  men  to  find 
exactly  the  same.  Ten  of  the  world's  greatest  authorities 
all  differ  slightly  in  the  weight  of  a  cubic  foot  of  water  at  the 
same  temperature.  They  differ  very  little,  to  be  sure,  and 
very  likely  as  much  from  the  difficulty  of  getting  the  standard 
vessel  of  measurement  the  same  in  all  cases,  as  from  anything 
else.  It  is  impossible  for  one  man  to  make  two  vessels  alike 
in  size,  and  also  for  two  men  to  make  one  each  and  have  both 


362  PUMPING  ENGINES 

the  same  size.  Such  duplication  is  beyond  the  powers  of 
human  faculties;  but  they  get  them  near  enough  for  practical 
purposes,  and  very  much  nearer  than  the  results  can  be  read 
and  recorded  in  a  duty  test  of  a  pumping  engine. 

In  an  ordinary  duty  test  a  slight  disagreement  does  not  mat- 
ter so  very  much,  as  to  the  weight  of  a  cubic  foot  of  water,  so 
long  as  the  contract  duty  is  fully  met ;  but  in  a  duty  test  where 
money  as  a  bonus  or  a  penalty  is  to  be  charged  against  or 
credited  to  the  contractor,  according  to  the  duty  obtained  by 
the  engine,  some  absolute  figure  must  be  agreed  upon  for  the 
weight,  because  only  one  result  is  permissible.  The  writer 
after  many  observations,  and  consulting  many  authorities 
upon  the  subject,  has  arrived  at  62.42  Ibs.  for  the  weight  of  a 
cubic  foot  of  water  at  or  below  48  Fahrenheit,  and  above  that 
temperature  is  governed  by  circumstances  bearing  upon  the 
case  at  the  time  of  a  test. 

From  the  weight  and  capacity  per  revolution  the  result 
per  minute,  hour,  day,  or  any  other  period  of  time,  may  be 
easily  computed;  and  the  weight  of  water  so  found  multiplied 
by  the  correct  total  head  against  which  the  plungers  have 
worked  during  the  duty  test,  will  give  the  foot  pounds  of  work 
done,  and  against  which  the  weight  of  steam,  or  the  number 
of  heat  units,  a  e  to  be  charged  in  finding  the  final  results. 

Before  the  test  is  commenced,  the  various  substances  and 
instruments  needed  in  the  work  should  be  carefully  considered 
and  their  respective  values  agreed  upon,  so  that  a  unanimous 
decision  can  be  reached  when  the  test  is  finished.  And  it  is 
also  necessary  to  fix  certain  points  of  elevation  so  as  to  have 
proper  data  upon  which  to  calculate  at  any  time  needed;  such 
points  of  elevation  should  be  observed  and  recorded. 

Sometimes  in  testing  a  pumping  engine  for  duty,  instead  of 
weighing  the  ingoing  feed  water,  the  record  of  steam  consump- 
tion is  obtained  by  weighing  the  outcoming  water  of  condensa- 
tion where  a  surface  condenser  is  used  with  the  engine.  In 
such  a  case  the  steam  consumed  by  the  engine  and  its  appur- 
tenances is  taken  as  the  weight  of  the  condensed  steam  delivered 


f 
DUTY  TESTS  OF  PUMPING  ENGINES  363 

by  the  air  pump  from  the  surface  condenser;  the  weight  of 
the  condensed  steam  rejected  by  the  reheating  coils  of  the 
receivers  between  the  cylinders;  and  the  weight  of  the  con- 
densed steam  rejected  by  the  steam  jackets  of  the  engine,  plus 
any  amount  observed  as  leakage  or  loss  before  the  condensed 
steam  reaches  the  weighing  tanks  or  barrels,  and  plus  the 
amount  that  may  be  used  by  any  independent  appa;  atus  neces- 
sary for  the  operation  of  the  engine  itself.  All  of  these  amounts 
so  found  are  to  be  treated  the  same  as  similar  quantities  men- 
tioned in  the  feed  water  method  for  determining  the  steam 
consumption,  or  for  determining  the  heat  supplied  to  the  engine 
and  its  appurtenances.  With  this  method  of  finding  the  steam 
consumption  by  means  of  the  condensed  steam,  there  are  used 
the  same  means  for  determining  the  plunger  capacity  and 
load,  as  in  the  methods  already  described. 


INDEX 


A. 

Air  chambers: 

benefits  of 273 

general  use  of 266 

greater  use  of 270 

location  of 268 

practical  application  of.     .     269 

proportions  of      271 

strength  required  in    .     271-272 
Atmosphere,  the: 

height  of  lift  possible  from 

pressure  of 232 

natural  pressure  of      ...     230 
operation     called     suction 

from 230-231 

suction  lift  due  to    ...         229 
vacuum    test    of   pressure 

from 231 

Attachment: 

Worthington  high  duty,  116-117 


B. 

Boilers: 

basis    of   heating    surface, 
table  95 


efficiency  of  ... 
first  steam  boiler 
heating  surface  of 
items  affecting  . 
remarks  on  ... 
table  of  efficiencies 


79-80-81 
.  .  9 
.  .  94 
.  .  93 
.  .  102 
83 


table  of  heating  surface  .    .  96 

utilizing  waste  heat  of    .    .  103 
Brick: 

in  foundations 211 


C. 
Clearance: 

in  steam  cylinders  .    .     165-297 
Coal: 

heat  derived  from  ....  83 
slack  and  anthracite  .  .  89-90 
value  of  anthracite  .  .  .  88-89 
value  of  bituminous  ...  87 
Concrete: 

in  foundations 212 

voids  in 213 

Corliss: 

George  H.,  portrait  of    .    .       66 
Pawtucket  pumping  engine, . 

179-181 
pumping    engine    without 

steam  jackets 65 

valves  for  steam  cylinders,     293 
Costs: 

as  compared  with  different 

plants    .    .     225-226-227-228 
comparisons   of,  based  on 

low  duty 224 

for  and  against  high  duty     223 

of  boilers 218 

of       coal,       maintenance, 

wages,  etc 216-221 

of    pumping    per    million 

gallons 222 

of  pumping  plants  .    .     217-220 
Crank,  the: 

disputed  invention  of     .    .       14 
of       Holly       quadruplex 

engine 127 

load  on  pins  for 336 

materials  for 331 

of  steamboat  engines      .    .     127 


365 


366 


INDEX 


Crank,  the  (continued): 

pressing  fits  for 331 

Cross  compounds: 

Allis-Chalmers .  .  .  .  316-320 
frames  and  bedplates  for  .  320 
large  specimens  of  ....  326 
limited  capacity  of  ...  321 
limited  power  of  ....  320 
Platt  Iron  Works  .  .  316-320 
Snow  Steam  Pump  Works, 

316-320 

vertical 324 

Worthington 316 

Cross  Heads : 

cross-compound,     horizon- 
tal engines 308 

early  Gaskill  engines  ...     306 

forged    304-310 

generally 303-312 

later  Gaskill  engines  ...  307 
pressure  on  shoes  of  ...  312 
vertical  crank  engines,  310-311 
Worthington  engines, 

303-304-305-309 

Counter-bores: 

faulty  specimen  of  ....  281 
in  steam  cylinders  ....  301 


D. 


Duty: 

at   different   thermal  em 


ciencies - 

at  high  piston  speed  ...  43 

at  high  steam  pressure  .  .  44 
average  of  American 

engines  24 

different  expressions  of  .  .  28 

economic  steam 22 

from  1893  to  1906  ...  37 

items  affecting  in  boilers  .  93 

of  crank  engines 22 

of  Gaskill  engine 32 

of  Holly  quadruplex 

engine    ..*......  31 

of  the  crank  engine  ...  28 


Duty  (continued): 

first    duty   of   a    pumping 

engine 2 

of  present  time  with  1,000 

pounds  of  steam      ...       23 

on  coal      92 

per  100  pounds  of  coal, 

79-80-81-82 
percentage     of    coal     and 

steam 83 

present  high  record  ...  22 
relation  to  steam  pressure  25 
Reynolds  Hannibal  engine  33 
Reynolds  pumping  engines  158 
Savery,  Smeaton,  New- 

comen  and  Watt  engines  22 
Simpson  engine  at  Chicago,  30 
steam  compared  with  coal,  82 
with  and  without  experts,  186 
Worthington  high  and  low 

duty  engines 31 

Worthington   engine    with 

superheated  steam      .    .       23 
Duty  tests: 

calibration  of  instruments 

and  substances  for  360-361 
comparison  between  weirs 

and  meters  for     ....     336 

definition  of 343 

different  basis  for    ....     345 
leakage  from   boilers  dur- 
ing           348-349 

measurement    of    plungers 

for 358-359 

Mercury  column   for  load 

during 357 

moisture  in  steam  during, 

351-353 
per  1,000  pounds  of  steam, 

345-346-347 

per  1,000,000  heat  units,  351-352 
superheated  steam  in  .  350-353 
total  heat  units  consumed 

in 354 

weight    of    cubic    foot    of 

water  for  ....  355 


INDEX 


367 


Duty  tests  (continued)'. 

work    done    by    plungers 
during 355 


E. 

Efficiency. 

all  round  world's  economic 

record 44 

economy  of  highest  type  of 

pumping  engines      ...  46 

highest  thermal  record   .    .  44 

table  of  thermal 185 

Engines,  steam: 

Corliss,  operated  by  com- 
pressed air 49 

Hero's 9 

Papin's  model      11 

Expansion,  steam: 

dry  initial  steam  for   ...  26 
in  fast  and  slow  running 

engines      27 

in  a  Corning  engine     ...  27 

ideal  ratios  of,  table    ...  27 

lowest  terminal  pressure  of,  26 
relation  between   terminal 

and  mean  effective      .    .  35 
shown  by  Mariotte  curve.    47-62 

with  5  pounds  terminal  .    .  38 

with  7  pounds  terminal   .    .  38 

with  10  pounds  terminal    .  38 

Experts: 

before  buying  engines     .    .  193 

duty  tests  run  by    ....  94 
use  of     .    .                       .  91-193 


F. 

Foundations: 

anchor  bolt  washers  for  .  211 
concrete  for  ....  212-214 
concrete  piling  for  .  .  206-207 
cut  stone  and  rubble  work 

for      214 

engine  sole  plates  on  ...     214 


Foundations(con*  inued) : 

general 197 

grouting  of 211-212 

investment  in 199 

live  load  upon 198 

materials  for 211 

stone  and  brick  for     ...     211 

test  holes  for 205 

timber  piling  for  ....  211 
underpinning  building  walls 

for      189-202 

upon  rock 198 

voids  in  concrete  for    .     212-213 
Frames  and  bedplates: 

for  cross  compound  engines,  320 
for  horizontal  engines  .  .  314 
for  vertical  engines  321-322-323 
from  early  to  late  engines,  315 
galleries  and  platforms  for,  328 

general      313 

general  principles  of  ...  313 
large  Worthington  vertical 

engines 326-327 

science  of      314 

single  "A  "frames   .    .     324-325 


G. 
Gaskill: 

cross  head  of  engine  .  306-307 
cut  of  compound  engine  .  135 
cut  of  triple  engine  .  .  .  137 
date  of  appearance  of 

engine 13 

Harvey  F.,  portrait  of  .  .  134 
high  duty  pumping  engine, 

31,,  134-135-137-139-143 
latest  compound  ....  139 
number  of  engines  ....  143 


H. 
Heat: 

Carnot's  theory  oC  .    .    .    .       19 
effects   of,  on   compressed 
air  48 


368 


INDEX 


Heat  (continued) : 

Joule's  mechanical  equiva- 
lent of 20 

nature  of 1 

theory  of  heat  engines 
based  upon  thermody- 
namics    21 

units  of,  from  combustion 

of  coal 83 

Historical: 

Birth  of  James  Watt  .  .  12 
Carnot's  theory  of  heat  .  19 
crank  and  planet  wheel  .  14 

Hornblower      15 

jet    of    water    caused    by 

steam  pressure     ....        9 
Joule's    mechanical    equi- 
valent of  heat      ....       20 
Leupold's  pumping  engine,       13 
Leupold  and  Smeaton     .     11-12 

McNaught 16 

Papin's  steam  piston      .    .       10 

pump  valves 241 

principles  of  steam  engines,  18 
raising  water  by  steam 

power 8 

science  of  heat  and  ther- 
modynamics .  .  .  20-21 

steam  boiler 9 

suction  and  force  pump  .  9 
Watt's  monument  .  »  .  .,  19 
Watt's  specifications  .  .  14-15 

Woolf 16 

Holly: 

Birdsill,  portrait  of     ...     123 
quadruplex  pumping    en- 
gine  ....  31-123-124-133 
Hornblower: 

engine 15 

Horse  power: 

indicated       steam      horse 

power 99 

of  water  ends  of  pumping 

engines      98 

table  of,  indicated    ....     101 


I. 

Indicated  horse  power: 

steam 99 

table  of 101 

Initial : 

effects  of  steam  on  pistons,  42 
force  in  steam  engines  .  40-42 
pressure  on  pistons, 

282-284-285 

Installation  of  engines: 

in  a  new  building  ....  197 
in  an  old  building  ....  197 
of  pumping  engines.  .  197-214 
unit  of  capacity  for  ...  202 
unit  of  plant  for  ....  204 

Investment  values: 

basis  for  boilers 218 

basis  for  plants  in  tables    .217 
basis  for  pumping  machin- 
ery      218 

capacities  for 222 

data  for  tables     .    .    .     215-216 
of  pumping  plants  gener- 
ally         215-228 

prices  of  engines  for  ...  216 
tables  giving  data  for, 

219-220-221 


L. 
Leavitt : 

E.  D.,  portrait  of      ....     182 
Lawrence  pumping  engine, 

183-299 

steam  cylinder     .    .    .     298-299 
steam  jacket     ....    298-299 


M. 

Mariotte  curve: 

advantages  of  working  by,  50-51 
birth  and  death  of  Edme 

Mariotte    .......       47 

curve  actually  obtained  in 

practice 49 


INDEX 


369 


Mariotte  curve  (continued) : 
explained    by    glass    tube 

and  mercury 48 

in  single  large  cylinder  in 

practice 56 

law  of  curve  of  expanding 

gases      47 

reduction  in  range  of  tem- 
perature           55 

theoretical,  in  single  cylin- 
der            52 

theoretical,  through  three 

cylinders 53-54 

through  three  cylinders  in 

practice,     57-58-59-60-61-62 
Materials  for  pumping  engines: 

babbitt  metal 342 

composition      342 

cranks  and  fly  wheels  for  .     331 

crank  pin  load 336 

cylinders  for 341 

fly  wheels  for 341 

generally 329-342 

inspection  and  testing  .  .  342 
perfect  castings  .  .  .  248-249 
pillow  blocks  for  .  .  337-338 
pillow  blocks  for  vertical 

engines      338-339 

pressing  fots  for 331 

proportions  of  cranks  .  .  336 
Rankine's  formula  for 

shafts     ....    333-334-335 

steel  castings 341 

strength  of  forgings  .  .  .  330 
temperatures  and  pressures 

for  forgings 330 

test  specimens  of     ....     330 

wrought  iron 342 

McNaught : 

compound  steam  engine,     16-17 
Mechanical  efficiency : 

of  large  pumping  engines    .     165 

of  plungers 250 

of  pumping  engines     ...     100 
of  plungers  and  valves  in 
pumps 250 


P. 


Pistons,  steam : 

effects  of  counterbore  on, 

281-282 

general  principles  ....  274 
initial  pressure  on,  282-284-285 
most  effective  form  of  .  .  275 
packing  rings  for  ....  275 
56-inch  piston  .  282-283-284 
84-inch  piston  .  .  .  284-285 
weight  of  56-inch  piston  .  284 
weight  of  84-inch  piston  .  285 
16-inch  piston  .  276-277-278 
23-inch  piston  .  .  .  278-279 
weight  of  30-inch  piston  .  282 

Plungers : 

best  known  forms  of  ...  256 
best  speed  for  ....  255-256 
centre  packed  .  .  261-262-263 
correct  measurement  of  .  .  251 
description  and  nature  of  .  249 
different  combinations  of  .  267 

differential 263 

ends  of  plungers      ....     249 
fire  engine  plunger  experi- 
ment           258-259 

inside  packed  .  .  .  259-260 
mechanical  efficiency  of  .  250 
motion  diagram  for  crank 

engines      252-253 

motion  of  direct  acting  .  .  254 
office  or  work  of  ....  249 
outside  packed  .  .  .  259-261 
perfect  displacement  by  .  251 
plunger  and  ring  .  256-257-258 
rod  connection  of  .  .  264-265 

single  acting 263 

two  distinct  principles  of, 

250-251 

Pumping  engines: 

adapted  to  conditions,     184-196 

comparisons 141 

compound  non  condensing      168 
Corliss   Pawtucket  pump- 
ing engine     ....    179-181 


370 


INDEX 


Pumping  engines  (continued): 

cross  compound   .     171-172-173 
cut   of  Gaskill   compound 

engine 135 

cut  of  Gaskill  triple  engine,     137 
cut '  of    Reynolds    original 

triple  engine 155 

cut  of  high  duty  Worthing- 

ton  engine 113 

cut  of  original   Worthing- 

ton  engine 107 

d'Auria  pumping  engine, 

176-177-178 

date  of  appearance  of  Gas- 
kill  engine     13 

date    of    introduction    of 

Holly  quadruplex  ...  124 
difference  between  Worth- 

ington  and  Gaskill  ...  34 
early  history  of  Reynolds 

engine  ....  144-145-146 
first  suction  and  forcing  .  9 
first  appearance  of  Worth- 

ington  duplex  ....  30-31 
first  triple  pumping  engine 

in  the  world 156 

Gaskill  high  duty    ....       31 
Holly  quadruplex    .    .     123-124 

LeupokTs      11-13 

Newcomen's 11-12 

original  design  of  Reynolds 

triple  expansion  engine,  144 
Platt  Iron  Works  pumping 

engines      .    .    .     173-178-179 

present  status  of 104 

principal  elements  of      .    .       18 
procedure  in  buying, 

189-190-191-192 
record  of  durability  ...  114 
regular  standards  ....  106 
regulating  speed  of  .  .  131-132 
Reynolds  self-contained 

engine 158 

Reynolds  North  Point,  Mil- 
waukee, triple  engine  .    .     157 
Reynolds  Hannibal  engine,     154 


Pumping  engines  (continued) : 
Reynolds  Allegheny  engines, 

147-148 
Reynolds     vertical     triple 

engine 144-166 

Savery's 10 

section    of    Worthington 

high  duty 115 

Shedd's  Providence  engine,  181 
Shields'  Cincinnatti  engine,  181 
Simpson's  crank  engine  .  .  29 
triple  non  condensing  .  .  168 
various  types  and  classes, 

167-183 

vertical  compound  .    .     174-175 
Worthington    duplex,    de- 
scription         106-122 

Worthington  at  Newton  .  110 
Worthington  vertical  .  .  119 
Worthington  low  duty 

triple 117 

Worthington  high  duty  .    .       31 
Pumping  Plants: 

best  conditions  for  ....       93 

unit  for 64 

Pumping  water:  , 

actual  conditions  of    ...       93 
experience  of  Chicago     .    .       94 
first   duty  of    a   pumping 
engine 2 


R. 

Reynolds: 

Allegheny  pumping  engines, 

147-148-149 

cage  pump  valves,   150-151-152 

early    type     of    pumping 
engines      .    .    .     144-145-146 

Hannibal  pumping  engine,     154 

North    Point,    Milwaukee, 
pumping  engine  ....     157 

number  of  Reynolds  pump- 
ing engines 166 

original     triple     pumping 
engine    ....     144-155-156 


INDEX 


371 


Reynolds  (continued): 

portrait  of  Edwin  Reynolds,     144 
self-contained        pumping 

engine 158 

vertical     triple     pumping 

engine 144-166 


S. 


Selection  of  a  pumping  engine: 

data  for 191 

for  closed  system  of  pipes, 

187-188 

for  reservoir  work    ....     186 
specifications  for .    .    .     195-196 
types  and  classes  for  differ- 
ent service 188 

with    consumers    involved 

in  the  question     .    .     186-187 
Simpson: 

typa  at  Chicago 29 

pumping  engine 29 

Steam : 

economy  of  pumping  en- 
gines,             45 

first  piston 10 

first  turbine 9 

'form  of  gas 1 

general    principlss   of   pis- 
tons     274 

initial  pressures  on  pistons, 

277-278-282 

packing  rings  of  pistons  for,  275 
per  pump  horse  power  .  .  96 
piston,  16-inch  .  276-277-278 
piston,  23-inch  .  .  .  278-279 
piston,  three  ring  form  of, 

279-280 

piston,  30-inch  .  280-281-282 
piston,  56-inch  .  232-283-284 
piston,  84-inch  .  .  .  234-285 
valve  gear  of  Holly  quad- 

ruplex  engine 123 

Steam  cylinders: 

boring  of 301 


PAGE 

Steam  cylinders  (con'.inuec,) : 

clearance  in 297 

Corliss  valves  for     ....     293 

covering  of 298 

counterbores  for  ....  301 
different  jackets  for, 

290-291-292-298-299 

in  general 287-292 

jacket  piping  for 289 

jacket  pressures  for  .  .  .  289 
poppet  valves  for  ....  295 
ribs  and  pipe  nozzles  for  .  294 

side  pipes  for 293 

valves  across  the  heads  of,     296 
Steam  jackets: 

absence    of,  on    a    Corliss 

pumping  engine   ....       65 
apparent    temperature    of 

cylinder  walls  .    .       76-77-78 
arrangement  of  piping  for, 

159-160 
cost    of   engine    with    and 

without 70-71 

different     conditions     and 

classes  of  engines  with     .       70 
different  forms  of, 

290-291-292-298-299 
effects  of  varying  steam  in,  64 
effect  on  compound  duplex,  65 
experience  with  varying 

steam  in 71-72 

general  statement  of  ...       63 
percentage  of  steam   con- 
densed in       66-67 

per  cubic  foot  of  cylinder     .       56 

piping  for 289 

pressure  in,  for  good  work,         67 

pressures  in 160-289 

proper  combination  of,  with 

cut  off 64 

range  of     temperature     in 

cylinders 73-74-75 

side  and  head  jacketing,  68-69 
table  of  conditions  for  .  .  68 
table  showing  increased 

use  of  steam  in  72 


INDEX 


Stone: 

cut  stone  for  foundations    .     214 
rubble  stonework  for  foun- 
dations   214 

Suction: 

actual  operation  of  .    .     230-231 

choice  of 233 

details  of  .  .  .  234-235-236-37 
height  of  lift  possible  ...  232 
lift  and  pipes  ....  229-239 

limited  force  of 229 

normal  conditions  before    .     229 

pipe  joints  for      238 

table  of  pipe  details  for  .  .  239 
table  of  pipes  for  ....  237 
vacuum  test  of 231 

T. 

Thermal  efficiency: 

duties  and  thermal  efficien- 
cies    . 44 

highest  record  of      ....       44 

table  of 185 

Triple  expansion : 

first  appearance  in  pump- 
ing engines 35 

original      triple      pumping 

engine    ....     144-155-156 
Reynolds  vertical  pumping 
engines      144-166 

V. 
Valves: 

across  cylinder  heads      .    .  296 

action  of    ......;.  240 

area  through  seats  of,     245-246 

Corliss  steam 293 

Corliss    steam    valves    on 

Worthington  engines     .  120 

Cornish  pump  valves  ...  150 

experiment  of  steam  ...  161 

for  various  types  of  engines,  246 

Gaskill  pump  valves    .    .    .  140 

history  of 241 

lift  of  pump  valves  .    .     243-244 

poppet  for  steam      ....  295 


PAGE 

Valves  (continued): 

pump  discharge  valves  .  .  248 
pump  valves  generally,  240-248 
seats  for  pump  valves, 

241-242-243 

steam  valves  across  cylin- 
der heads      152 

standard  pump  valves  .  .  Ill 
steam  engine,  Humphry 

Potter 11 

W. 

Water  passages: 

few  simple  principles  of  .    .     240 

generally 240-248 

importance    of    easy    flow 
through 240 

Water  ram: 

effects  of 272 

Water  supply: 

various  systems  of  ....         6 

Watt,  James: 

date  of  birth 12 

methods 13-14 

monument  in  Westminster 

Abby 19 

principal   elements    of   his 

engine    . 18 

portrait  of  —  frontispiece, 
pumping  engines      .    .  17-20-21 
specifications  for  engines  .  14-16 

Woolf: 

his  engine      .......       16 

Worthington : 

cross    heads    of    pumping 

engines  .  .  303-304-305-309 
cut  of  high  duty  engine  .  .  113 
cut  of  original  engine  ...  107 
duplex  engine, 

30-31-106-115-117-122 
Henry  R.,  portrait  of  .  .  108 
high  duty  engine  .  .  .»  .  31 
later  high  duty  engines  .  .  117 

low  duty  triple 117 

number  of  engines  ...  122 
record  of  durability  ...  115 
vertical  engines 119 


UNIVERSITY 


AUG  15  1980 

8K.CML 


20074 


TT90& 
HS 


1 73029 


